Help: Fix typo in dependency provider method keyword

The cmake.vim file is generated by scanning for keyword-like
strings in the docs. Update the corresponding wrong entry
there too directly for now, which will fix the wrong entry until
the next full regeneration of the file.

Fixes: #25503

Auxiliary/vim/syntax/cmake.vim

@@ -2764,7 +2764,6 @@ syn keyword cmakeKWcmake_language contained
             \ DIRECTORY
             \ EVAL
             \ FALSE
-            \ FETCHCONTENT_MAKEAVAILABE_SERIAL
             \ FETCHCONTENT_MAKEAVAILABLE_SERIAL
             \ FETCHCONTENT_SOURCE_DIR_
             \ FETCHCONTENT_TRY_FIND_PACKAGE_MODE

Help/command/cmake_language.rst

@@ -317,7 +317,7 @@ be one of the ``<methods>`` that was specified when setting the provider.
   implementation as part of its processing, it can do so by including the
   ``BYPASS_PROVIDER`` keyword as one of the arguments.
 
-``FETCHCONTENT_MAKEAVAILABE_SERIAL``
+``FETCHCONTENT_MAKEAVAILABLE_SERIAL``
   The ``<method-specific-args>`` will be everything passed to the
   :command:`FetchContent_Declare` call that corresponds to the requested
   dependency, with the following exceptions: