Help: for message(FATAL_ERROR), document nonzero exit code

Help/command/message.rst

@@ -32,6 +32,9 @@ influences the way the message is handled:
 ``FATAL_ERROR``
   CMake Error, stop processing and generation.
 
+  The :manual:`cmake(1)` executable will return a non-zero
+  :ref:`exit code <CMake Exit Code>`.
+
 ``SEND_ERROR``
   CMake Error, continue processing, but skip generation.
 

Help/manual/cmake.1.rst

@@ -1065,9 +1065,10 @@ To view the presets available for a project, use
 Return Value (Exit Code)
 ========================
 
-Upon regular termination, the **cmake** executable returns the exit code 0.
+Upon regular termination, the ``cmake`` executable returns the exit code ``0``.
+
 If termination is caused by the command :command:`message(FATAL_ERROR)`,
-then a non-zero exit code is returned.
+or another error condition, then a non-zero exit code is returned.
 
 
 See Also