Merge pull request #232 from wilzbach/fix-17262

Issue 17262 - Better docs for rdmd
merged-on-behalf-of: Vladimir Panteleev <github@thecybershadow.net>

rdmd.d

@@ -809,6 +809,7 @@ addition to compiler options, rdmd recognizes the following options:
                      (needs dmd's option `-of` to be present)
   --man              open web browser on manual page
   --shebang          rdmd is in a shebang line (put as first argument)
+  --tmpdir           set an alternative temporary directory
 ".format(defaultCompiler, defaultExclusions);
 }