docs: Move the threads-deprecated SECTION

Move it to a separate page so an overview of the deprecated threading
API can be given.

Signed-off-by: Philip Withnall <pwithnall@gnome.org>

Helps: #3037

docs/reference/glib/glib.toml.in

@@ -66,6 +66,8 @@ content_files = [
   "goption.md",
   "data-structures.md",
   "unicode.md",
+
+  "threads-deprecated.md",
 ]
 content_images = [
   "file-name-encodings.png",

docs/reference/glib/meson.build

@@ -160,6 +160,7 @@ expand_content_files = [
   'running.md',
   'testing.md',
   'threads.md',
+  'threads-deprecated.md',
   'markup.md',
   'goption.md',
   'data-structures.md',

docs/reference/glib/threads-deprecated.md

@@ -0,0 +1,37 @@
+Title: Deprecated Thread API
+SPDX-License-Identifier: LGPL-2.1-or-later
+SPDX-FileCopyrightText: 2011 Allison Lortie
+
+# Deprecated Thread API
+
+These APIs are deprecated.  You should not use them in new code.
+This section remains only to assist with understanding code that was
+written to use these APIs at some point in the past.
+
+Deprecated thread creation/configuration functions:
+
+ * [type@GLib.ThreadPriority]
+ * [type@GLib.ThreadFunctions]
+ * [func@GLib.Thread.init]
+ * [func@GLib.Thread.get_initialized]
+ * [method@GLib.Thread.set_priority]
+ * [func@GLib.Thread.foreach]
+ * [func@GLib.Thread.create]
+ * [func@GLib.Thread.create_full]
+
+Deprecated static variants of locking primitives:
+
+ * [type@GLib.StaticMutex]
+ * [type@GLib.StaticRecMutex]
+ * [type@GLib.StaticRWLock]
+ * [type@GLib.StaticPrivate]
+
+Deprecated dynamic allocation of locking primitives:
+
+ * [func@GLib.Private.new]
+ * [func@GLib.Mutex.new]
+ * [method@GLib.Mutex.free]
+ * [func@GLib.Cond.new]
+ * [method@GLib.Cond.free]
+ * [method@GLib.Cond.timed_wait]
+

glib/deprecated/gthread-deprecated.c

@@ -40,17 +40,6 @@
 
 /* {{{1 Documentation */
 
-/**
- * SECTION:threads-deprecated
- * @title: Deprecated thread API
- * @short_description: old thread APIs (for reference only)
- * @see_also: #GThread
- *
- * These APIs are deprecated.  You should not use them in new code.
- * This section remains only to assist with understanding code that was
- * written to use these APIs at some point in the past.
- **/
-
 /**
  * GThreadPriority:
  * @G_THREAD_PRIORITY_LOW: a priority lower than normal