doc: Deprecate use-stable-kde.

doc/index.docbook

@@ -2556,23 +2556,11 @@ system.
 <row id="conf-use-stable-kde">
 <entry>use-stable-kde</entry>
 <entry>Can't be overridden</entry>
-<entry><para>By default, &kdesrc-build; will build the main line of &kde;
-development (trunk or master branch). You can use the &branch; option globally
-or for a module in order to switch to a stable release. However, this is not
-convenient as a lot of branch options would have to be added to the
-configuration file and kept up to date when the next stable version is
-released.</para>
-
-<para>So, if you set this option to <replaceable>true</replaceable>,
-&kdesrc-build; will (for a given module) automatically download the version of
-that module which is marked as stable in kde_projects.xml.</para>
-
-<para>This option can only be set globally, but you can still use the &branch;
-or &tag; options for a module to override this option.
-This way you can easily choose to download current stable &kde; version by default
-while still choosing the current development version of specific modules.
-</para>
+<entry>
+<para>This option is deprecated and will be removed (again) in a future release.</para>
 
+<para>Please use the <option><link linkend="conf-branch-group">branch-group</link></option>
+instead, which offers more selectivity.</para>
 </entry>
 </row>