treewide: migrate doc comments

[hsjobeki]

Not ready to be merged yet.

Description of changes

Reformat doc-comments according to RFC145.

• Every doc-comment starts with /** and ends with the regular */
• nixdoc format is automatically detected and migrated into valid markdown.
• Content and comment itself is re-indented to be a multiple of 2 (No hitting whitespace anymore yay!)

Some handwork is still needed.

This PR is automatically updated every day.

demo of the rendered comments: https://noogle.dev

• Every doc-comment is one markdown document.

This breaks compatibility with the existing manual. (Migrations ongoing)

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 23.11 Release Notes (or backporting 23.05 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.