[HUDSON-4209] Expanded help that this option is forced when multiple modules...

[HUDSON-4209] Expanded help that this option is forced when multiple modules are specified for checkout.

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@20636 71c3de6d-444a-0410-be80-ed276b4c234a

war/resources/help/_cvs/legacy.html

@@ -4,6 +4,9 @@
   then put everything below. With this option checked off, there will be no more
   such unnecessary intermediate directories.
 
+  <p>
+  If you have multiple modules to check out, this option is forced (otherwise they'll overlap.) 
+
   <p>
   This affects other path specifiers, such as artifact archivers --- you now specify
   "build/foo.jar" instead of "foo/build/foo.jar".