Merge pull request #305370 from stuebinm/docs-remove-emacs-docbook-section

nixos/emacs: remove docbook section in the documentation

nixos/modules/services/editors/emacs.md

@@ -366,44 +366,3 @@ convenient if you regularly edit Nix files.
 You can use `woman` to get completion of all available
 man pages. For example, type `M-x woman <RET> nixos-rebuild <RET>.`
 
-### Editing DocBook 5 XML Documents {#sec-emacs-docbook-xml}
-
-Emacs includes
-[nXML](https://www.gnu.org/software/emacs/manual/html_node/nxml-mode/Introduction.html),
-a major-mode for validating and editing XML documents. When editing DocBook
-5.0 documents, such as [this one](#book-nixos-manual),
-nXML needs to be configured with the relevant schema, which is not
-included.
-
-To install the DocBook 5.0 schemas, either add
-{var}`pkgs.docbook5` to [](#opt-environment.systemPackages)
-([NixOS](#sec-declarative-package-mgmt)), or run
-`nix-env -f '<nixpkgs>' -iA docbook5`
-([Nix](#sec-ad-hoc-packages)).
-
-Then customize the variable {var}`rng-schema-locating-files` to
-include {file}`~/.emacs.d/schemas.xml` and put the following
-text into that file:
-::: {.example #ex-emacs-docbook-xml}
-### nXML Schema Configuration (`~/.emacs.d/schemas.xml`)
-
-```xml
-<?xml version="1.0"?>
-<!--
-  To let emacs find this file, evaluate:
-  (add-to-list 'rng-schema-locating-files "~/.emacs.d/schemas.xml")
--->
-<locatingRules xmlns="http://thaiopensource.com/ns/locating-rules/1.0">
-  <!--
-    Use this variation if pkgs.docbook5 is added to environment.systemPackages
-  -->
-  <namespace ns="http://docbook.org/ns/docbook"
-             uri="/run/current-system/sw/share/xml/docbook-5.0/rng/docbookxi.rnc"/>
-  <!--
-    Use this variation if installing schema with "nix-env -iA pkgs.docbook5".
-  <namespace ns="http://docbook.org/ns/docbook"
-             uri="../.nix-profile/share/xml/docbook-5.0/rng/docbookxi.rnc"/>
-  -->
-</locatingRules>
-```
-:::