[gtk/doc-chapters-markdown] docs: Drop a long-stale file

[Matthias Clasen <matthiasc src gnome org>]

commit 0ec8c5c0ed54e9fb20559ed919c1306f383fe3fe
Author: Matthias Clasen <mclasen redhat com>
Date:   Sun May 24 10:57:52 2020 -0400

    docs: Drop a long-stale file
    
    The other_software.xml section has not been included in
    the docs since 2.x, as far as I can tell. It was clearly
    written before GIO existed.

 docs/reference/gtk/meson.build        |   1 -
 docs/reference/gtk/other_software.xml | 211 ----------------------------------
 2 files changed, 212 deletions(-)
---
diff --git a/docs/reference/gtk/meson.build b/docs/reference/gtk/meson.build
index 536d5a90f6..9f7ac480d4 100644
--- a/docs/reference/gtk/meson.build
+++ b/docs/reference/gtk/meson.build
@@ -351,7 +351,6 @@ content_files = [
   'gtk4-query-settings.xml',
   'gtk4-update-icon-cache.xml',
   'gtk4-widget-factory.xml',
-  'other_software.xml',
   'overview.xml',
   'question_index.xml',
   'resources.xml',