Help: Document that ASM should be enabled last

ASM should be enabled after C and/or CXX because we consider the
compilers for those languages as possible assemblers.

Issue: #17532

Help/command/enable_language.rst

@@ -10,7 +10,10 @@ Enable a language (CXX/C/Fortran/etc)
 This command enables support for the named language in CMake.  This is
 the same as the project command but does not create any of the extra
 variables that are created by the project command.  Example languages
-are CXX, C, Fortran.
+are ``CXX``, ``C``, ``CUDA``, ``Fortran``, and ``ASM``.
+
+If enabling ``ASM``, enable it last so that CMake can check whether
+compilers for other languages like ``C`` work for assembly too.
 
 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

Help/command/project.rst

@@ -46,11 +46,15 @@ variable will be set to its argument. The argument must be a string with short
 description of the project (only a few words).
 
 Optionally you can specify which languages your project supports.
-Example languages are ``C``, ``CXX`` (i.e.  C++), ``Fortran``, etc.
+Example languages include ``C``, ``CXX`` (i.e.  C++), ``CUDA``,
+``Fortran``, and ``ASM``.
 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.
 
+If enabling ``ASM``, list it last so that CMake can check whether
+compilers for other languages like ``C`` work for assembly too.
+
 If a variable exists called :variable:`CMAKE_PROJECT_<PROJECT-NAME>_INCLUDE`,
 the file pointed to by that variable will be included as the last step of the
 project command.