invoke.texi: update -fdiagnostics-show-cwe for analyzer

gcc/ChangeLog:
	* doc/invoke.texi (-fdiagnostics-show-cwe): Add note that some of
	the analyzer options provide CWE identifiers.

gcc/ChangeLog

 2020-01-14  David Malcolm  <dmalcolm@redhat.com>
 
+	* doc/invoke.texi (-fdiagnostics-show-cwe): Add note that some of
+	the analyzer options provide CWE identifiers.
+
+2020-01-14  David Malcolm  <dmalcolm@redhat.com>
+
 	* tree-diagnostic-path.cc (path_summary::event_range::print):
 	When testing for UNKNOWN_LOCATION, look through ad-hoc wrappers
 	using get_pure_location.

gcc/doc/invoke.texi

@@ -4076,7 +4076,8 @@ the vertical bars and the ``char *'' and ``long int'' text).
 @opindex fdiagnostics-show-cwe
 Diagnostic messages can optionally have an associated
 @url{https://cwe.mitre.org/index.html, CWE} identifier.
-GCC itself does not do this for any of its diagnostics, but plugins may do so.
+GCC itself only provides such metadata for some of the @option{-fanalyzer}
+diagnostics.  GCC plugins may also provide diagnostics with such metadata.
 By default, if this information is present, it will be printed with
 the diagnostic.  This option suppresses the printing of this metadata.