CONTRIBUTING file for issues

CONTRIBUTING

+If you're filing an issue, here are the things which will help us a lot:
+
+* State your GHC version.
+
+* State your platform, OS and distribution if applicable.
+
+* State your cabal version if applicable.
+
+* Tell us how to replicate the problem. If we can't replicate it, we
+  can't fix it.
+
+* If the problem involves running Haddock on some source, please
+  include the sample on which we can replicate, the smaller/cleaner
+  the better. Include some images if you think it will help us.
+
+* Include any other info you think might be relevant (sandbox? unusual
+  setup?).