Help: Restore project command docs for default languages and NONE

In commit b787be2714 (Help: Update supported languages in project and
enable_language, 2023-01-20, v3.26.0-rc1~53^2) the relevant paragraph
was accidentally moved to the `enable_language` command documentation.

Fixes: #25016

Help/command/enable_language.rst

@@ -13,10 +13,6 @@ variables that are created by the project command.
 
 .. include:: SUPPORTED_LANGUAGES.txt
 
-By default ``C`` and ``CXX`` are enabled if no language options are given.
-Specify language ``NONE``, or use the ``LANGUAGES`` keyword and list no languages,
-to skip enabling any languages.
-
 This command must be called in file scope, not in a function call.
 Furthermore, it must be called in the highest directory common to all
 targets using the named language directly for compiling sources or

Help/command/project.rst

@@ -105,6 +105,9 @@ The options are:
 
 .. include:: SUPPORTED_LANGUAGES.txt
 
+By default ``C`` and ``CXX`` are enabled if no language options are given.
+Specify language ``NONE``, or use the ``LANGUAGES`` keyword and list no languages,
+to skip enabling any languages.
 
 The variables set through the ``VERSION``, ``DESCRIPTION`` and ``HOMEPAGE_URL``
 options are intended for use as default values in package metadata and documentation.