doc: explicit Markdown anchors for top-level headings; remove metadata

I used the existing anchors generated by Docbook, so the anchor part
should be a no-op. This could be useful depending on the
infrastructure we choose to use, and it is better to be explicit than
rely on Docbook's id generating algorithms.

I got rid of the metadata segments of the Markdown files, because they
are outdated, inaccurate, and could make people less willing to change
them without speaking with the author.

19 files changed, 19 insertions, 76 deletions

diff --git a/doc/builders/packages/cataclysm-dda.section.md b/doc/builders/packages/cataclysm-dda.section.md
index ae2ee56a010..1173fe32ada 100644
--- a/doc/builders/packages/cataclysm-dda.section.md
+++ b/doc/builders/packages/cataclysm-dda.section.md
@@ -1,4 +1,4 @@
-# Cataclysm: Dark Days Ahead
+# Cataclysm: Dark Days Ahead {#cataclysm-dark-days-ahead}
 
 ## How to install Cataclysm DDA
 
diff --git a/doc/builders/trivial-builders.chapter.md b/doc/builders/trivial-builders.chapter.md
index c39803fbe33..32944567c05 100644
--- a/doc/builders/trivial-builders.chapter.md
+++ b/doc/builders/trivial-builders.chapter.md
@@ -37,7 +37,7 @@ This works just like `runCommand`. The only difference is that it also provides
 
 Variant of `runCommand` that forces the derivation to be built locally, it is not substituted. This is intended for very cheap commands (<1s execution time). It saves on the network roundrip and can speed up a build.
 
-::: {.note}
+::: note
 This sets [`allowSubstitutes` to `false`](https://nixos.org/nix/manual/#adv-attr-allowSubstitutes), so only use `runCommandLocal` if you are certain the user will always have a builder for the `system` of the derivation. This should be true for most trivial use cases (e.g. just copying some files to a different location or adding symlinks), because there the `system` is usually the same as `builtins.currentSystem`.
 :::
 
diff --git a/doc/languages-frameworks/agda.section.md b/doc/languages-frameworks/agda.section.md
index 5ba4e285f42..66b4a208302 100644
--- a/doc/languages-frameworks/agda.section.md
+++ b/doc/languages-frameworks/agda.section.md
@@ -1,9 +1,4 @@
----
-title: Agda
-author: Alex Rice (alexarice)
-date: 2020-01-06
----
-# Agda
+# Agda {#agda}
 
 ## How to use Agda
 
diff --git a/doc/languages-frameworks/android.section.md b/doc/languages-frameworks/android.section.md
index f4f6c086a80..cfbacf1bccd 100644
--- a/doc/languages-frameworks/android.section.md
+++ b/doc/languages-frameworks/android.section.md
@@ -1,9 +1,4 @@
----
-title: Android
-author: Sander van der Burg
-date: 2018-11-18
----
-# Android
+# Android {#android}
 
 The Android build environment provides three major features and a number of
 supporting features.
diff --git a/doc/languages-frameworks/crystal.section.md b/doc/languages-frameworks/crystal.section.md
index af0853dbf75..74790132974 100644
--- a/doc/languages-frameworks/crystal.section.md
+++ b/doc/languages-frameworks/crystal.section.md
@@ -1,4 +1,4 @@
-# Crystal
+# Crystal {#crystal}
 
 ## Building a Crystal package
 
diff --git a/doc/languages-frameworks/emscripten.section.md b/doc/languages-frameworks/emscripten.section.md
index 3663f962d5f..8a47a7b320a 100644
--- a/doc/languages-frameworks/emscripten.section.md
+++ b/doc/languages-frameworks/emscripten.section.md
@@ -1,4 +1,4 @@
-# Emscripten
+# Emscripten {#emscripten}
 
 [Emscripten](https://github.com/kripken/emscripten): An LLVM-to-JavaScript Compiler
 
diff --git a/doc/languages-frameworks/haskell.section.md b/doc/languages-frameworks/haskell.section.md
index 67318a5b746..1fda505a225 100644
--- a/doc/languages-frameworks/haskell.section.md
+++ b/doc/languages-frameworks/haskell.section.md
@@ -1,10 +1,4 @@
----
-title: User's Guide for Haskell in Nixpkgs
-author: Peter Simons
-date: 2015-06-01
----
-
-# Haskell
+# Haskell {#haskell}
 
 The documentation for the Haskell infrastructure is published at
 <https://haskell4nix.readthedocs.io/>. The source code for that
diff --git a/doc/languages-frameworks/idris.section.md b/doc/languages-frameworks/idris.section.md
index f071b9ce178..2d06c4a19de 100644
--- a/doc/languages-frameworks/idris.section.md
+++ b/doc/languages-frameworks/idris.section.md
@@ -1,4 +1,4 @@
-# Idris
+# Idris {#idris}
 
 ## Installing Idris
 
diff --git a/doc/languages-frameworks/ios.section.md b/doc/languages-frameworks/ios.section.md
index 768e0690b96..a162e8d19fd 100644
--- a/doc/languages-frameworks/ios.section.md
+++ b/doc/languages-frameworks/ios.section.md
@@ -1,9 +1,4 @@
----
-title: iOS
-author: Sander van der Burg
-date: 2019-11-10
----
-# iOS
+# iOS {#ios}
 
 This component is basically a wrapper/workaround that makes it possible to
 expose an Xcode installation as a Nix package by means of symlinking to the
diff --git a/doc/languages-frameworks/lua.section.md b/doc/languages-frameworks/lua.section.md
index a0e9917b8ec..248e5971818 100644
--- a/doc/languages-frameworks/lua.section.md
+++ b/doc/languages-frameworks/lua.section.md
@@ -1,10 +1,4 @@
----
-title: Lua
-author: Matthieu Coudron
-date: 2019-02-05
----
-
-# User's Guide to Lua Infrastructure
+# User's Guide to Lua Infrastructure {#users-guide-to-lua-infrastructure}
 
 ## Using Lua
 
diff --git a/doc/languages-frameworks/maven.section.md b/doc/languages-frameworks/maven.section.md
index fe183e7ba3c..5f3979d69fd 100644
--- a/doc/languages-frameworks/maven.section.md
+++ b/doc/languages-frameworks/maven.section.md
@@ -1,10 +1,4 @@
----
-title: Maven
-author: Farid Zakaria
-date: 2020-10-15
----
-
-# Maven
+# Maven {#maven}
 
 Maven is a well-known build tool for the Java ecosystem however it has some challenges when integrating into the Nix build system.
 
diff --git a/doc/languages-frameworks/node.section.md b/doc/languages-frameworks/node.section.md
index 2120adfc0b4..847db22941f 100644
--- a/doc/languages-frameworks/node.section.md
+++ b/doc/languages-frameworks/node.section.md
@@ -1,5 +1,5 @@
-Node.js
-=======
+# Node.js {#node.js}
+
 The `pkgs/development/node-packages` folder contains a generated collection of
 [NPM packages](https://npmjs.com/) that can be installed with the Nix package
 manager.
diff --git a/doc/languages-frameworks/python.section.md b/doc/languages-frameworks/python.section.md
index 8a2fe2711c7..2dea2cb1bcc 100644
--- a/doc/languages-frameworks/python.section.md
+++ b/doc/languages-frameworks/python.section.md
@@ -1,4 +1,4 @@
-# Python
+# Python {#python}
 
 ## User Guide
 
diff --git a/doc/languages-frameworks/r.section.md b/doc/languages-frameworks/r.section.md
index d4e1617779c..d7154adc55b 100644
--- a/doc/languages-frameworks/r.section.md
+++ b/doc/languages-frameworks/r.section.md
@@ -1,5 +1,4 @@
-R
-=
+# R {#r}
 
 ## Installation
 
diff --git a/doc/languages-frameworks/rust.section.md b/doc/languages-frameworks/rust.section.md
index 0230993d3f0..a5b13217fe7 100644
--- a/doc/languages-frameworks/rust.section.md
+++ b/doc/languages-frameworks/rust.section.md
@@ -1,10 +1,4 @@
----
-title: Rust
-author: Matthias Beyer
-date: 2017-03-05
----
-
-# Rust
+# Rust {#rust}
 
 To install the rust compiler and cargo put
 
diff --git a/doc/languages-frameworks/texlive.section.md b/doc/languages-frameworks/texlive.section.md
index 9584c56bb52..c3028731f4e 100644
--- a/doc/languages-frameworks/texlive.section.md
+++ b/doc/languages-frameworks/texlive.section.md
@@ -1,4 +1,3 @@
-
 # TeX Live {#sec-language-texlive}
 
 Since release 15.09 there is a new TeX Live packaging that lives entirely under attribute `texlive`.
diff --git a/doc/languages-frameworks/titanium.section.md b/doc/languages-frameworks/titanium.section.md
index 7a97664ec59..57360f034b9 100644
--- a/doc/languages-frameworks/titanium.section.md
+++ b/doc/languages-frameworks/titanium.section.md
@@ -1,9 +1,4 @@
----
-title: Titanium
-author: Sander van der Burg
-date: 2018-11-18
----
-# Titanium
+# Titanium {#titanium}
 
 The Nixpkgs repository contains facilities to deploy a variety of versions of
 the [Titanium SDK](https://www.appcelerator.com) versions, a cross-platform
diff --git a/doc/languages-frameworks/vim.section.md b/doc/languages-frameworks/vim.section.md
index 84ad567e8c2..155dacc237b 100644
--- a/doc/languages-frameworks/vim.section.md
+++ b/doc/languages-frameworks/vim.section.md
@@ -1,9 +1,4 @@
----
-title: User's Guide for Vim in Nixpkgs
-author: Marc Weber
-date: 2016-06-25
----
-# Vim
+# Vim {#vim}
 
 Both Neovim and Vim can be configured to include your favorite plugins
 and additional libraries.
diff --git a/doc/preface.chapter.md b/doc/preface.chapter.md
index 549e42de7aa..64c921c711b 100644
--- a/doc/preface.chapter.md
+++ b/doc/preface.chapter.md
@@ -1,10 +1,4 @@
----
-title: Preface
-author: Frederik Rietdijk
-date: 2015-11-25
----
-
-# Preface
+# Preface {#preface}
 
 The Nix Packages collection (Nixpkgs) is a set of thousands of packages for the
 [Nix package manager](https://nixos.org/nix/), released under a