Update description to describe current limitations

Author: jhart-r7

modules/exploits/multi/http/cve_2014_9390.rb

@@ -33,7 +33,11 @@ def initialize(info = {})
         The third vulnerability with similar characteristics only affects
         Mercurial clients on Windows, where Windows "short names"
         (MS-DOS-compatible 8.3 format) are supported.
-    ),
+
+        Today this module only truly supports the first vulnerability (Git
+        clients on case-insensitive file systems) but has the functionality to
+        support the remaining two with a little work.
+      ),
       'License' => MSF_LICENSE,
       'Author' => [
         'Jon Hart <jon_hart[at]rapid7.com>' # metasploit module