nixos/emacs: restore example markup

these examples were turned into untitle anchors previously because at
the time supporting examples was not deemed necessary or useful. now
that we have them we can restore them though.

nixos/modules/services/editors/emacs.md

@@ -80,7 +80,8 @@ The first step to declare the list of packages you want in your Emacs
 installation is to create a dedicated derivation. This can be done in a
 dedicated {file}`emacs.nix` file such as:
 
-[]{#ex-emacsNix}
+::: {.example #ex-emacsNix}
+### Nix expression to build Emacs with packages (`emacs.nix`)
 
 ```nix
 /*
@@ -136,6 +137,7 @@ in
     pkgs.notmuch   # From main packages set
   ])
 ```
+:::
 
 The result of this configuration will be an {command}`emacs`
 command which launches Emacs with all of your chosen packages in the
@@ -158,19 +160,24 @@ and yasnippet.
 
 The list of available packages in the various ELPA repositories can be seen
 with the following commands:
-[]{#module-services-emacs-querying-packages}
+::: {.example #module-services-emacs-querying-packages}
+### Querying Emacs packages
+
 ```
 nix-env -f "<nixpkgs>" -qaP -A emacs.pkgs.elpaPackages
 nix-env -f "<nixpkgs>" -qaP -A emacs.pkgs.melpaPackages
 nix-env -f "<nixpkgs>" -qaP -A emacs.pkgs.melpaStablePackages
 nix-env -f "<nixpkgs>" -qaP -A emacs.pkgs.orgPackages
 ```
+:::
 
 If you are on NixOS, you can install this particular Emacs for all users by
 adding it to the list of system packages (see
 [](#sec-declarative-package-mgmt)). Simply modify your file
 {file}`configuration.nix` to make it contain:
-[]{#module-services-emacs-configuration-nix}
+::: {.example #module-services-emacs-configuration-nix}
+### Custom Emacs in `configuration.nix`
+
 ```
 {
  environment.systemPackages = [
@@ -179,6 +186,7 @@ adding it to the list of system packages (see
   ];
 }
 ```
+:::
 
 In this case, the next {command}`nixos-rebuild switch` will take
 care of adding your {command}`emacs` to the {var}`PATH`
@@ -192,7 +200,9 @@ If you are not on NixOS or want to install this particular Emacs only for
 yourself, you can do so by adding it to your
 {file}`~/.config/nixpkgs/config.nix` (see
 [Nixpkgs manual](https://nixos.org/nixpkgs/manual/#sec-modify-via-packageOverrides)):
-[]{#module-services-emacs-config-nix}
+::: {.example #module-services-emacs-config-nix}
+### Custom Emacs in `~/.config/nixpkgs/config.nix`
+
 ```
 {
   packageOverrides = super: let self = super.pkgs; in {
@@ -200,6 +210,7 @@ yourself, you can do so by adding it to your
   };
 }
 ```
+:::
 
 In this case, the next `nix-env -f '<nixpkgs>' -iA
 myemacs` will take care of adding your emacs to the
@@ -214,7 +225,9 @@ automatically generated {file}`emacs.desktop` (useful if you
 only use {command}`emacsclient`), you can change your file
 {file}`emacs.nix` in this way:
 
-[]{#ex-emacsGtk3Nix}
+::: {.example #ex-emacsGtk3Nix}
+### Custom Emacs build
+
 ```
 { pkgs ? import <nixpkgs> {} }:
 let
@@ -231,8 +244,9 @@ let
   });
 in [...]
 ```
+:::
 
-After building this file as shown in [the example above](#ex-emacsNix), you
+After building this file as shown in [](#ex-emacsNix), you
 will get an GTK 3-based Emacs binary pre-loaded with your favorite packages.
 
 ## Running Emacs as a Service {#module-services-emacs-running}
@@ -327,7 +341,10 @@ This will add the symlink
 
 The Emacs init file should be changed to load the extension packages at
 startup:
-[]{#module-services-emacs-package-initialisation}
+
+::: {.example #module-services-emacs-package-initialisation}
+### Package initialization in `.emacs`
+
 ```
 (require 'package)
 
@@ -337,6 +354,7 @@ startup:
 (setq package-enable-at-startup nil)
 (package-initialize)
 ```
+:::
 
 After the declarative emacs package configuration has been tested,
 previously downloaded packages can be cleaned up by removing
@@ -377,7 +395,9 @@ To install the DocBook 5.0 schemas, either add
 Then customize the variable {var}`rng-schema-locating-files` to
 include {file}`~/.emacs.d/schemas.xml` and put the following
 text into that file:
-[]{#ex-emacs-docbook-xml}
+::: {.example #ex-emacs-docbook-xml}
+### nXML Schema Configuration (`~/.emacs.d/schemas.xml`)
+
 ```xml
 <?xml version="1.0"?>
 <!--
@@ -397,3 +417,4 @@ text into that file:
   -->
 </locatingRules>
 ```
+:::