[NFC][clang][Driver] Specify options for <arg> with -save-temps=<arg> (#80921)

Author: lamb-j

clang/include/clang/Driver/Options.td

@@ -5392,7 +5392,9 @@ def regcall4 : Flag<["-"], "regcall4">, Group<m_Group>,
   MarshallingInfoFlag<LangOpts<"RegCall4">>;
 def save_temps_EQ : Joined<["-", "--"], "save-temps=">, Flags<[NoXarchOption]>,
   Visibility<[ClangOption, CC1Option, FlangOption, FC1Option]>,
-  HelpText<"Save intermediate compilation results.">;
+  HelpText<"Save intermediate compilation results. <arg> can be set to cwd for "
+  "current working directory, or obj which will save temporary files in the "
+  "same directory as the final output file">;
 def save_temps : Flag<["-", "--"], "save-temps">, Flags<[NoXarchOption]>,
   Visibility<[ClangOption, FlangOption, FC1Option]>,
   Alias<save_temps_EQ>, AliasArgs<["cwd"]>,