Update contributing guide explaining when it is ok to create an issue and how...

Update contributing guide explaining when it is ok to create an issue and how to get help otherwise.

CONTRIBUTING.md

@@ -3,11 +3,15 @@ requests.
 ## General guidelines
+If you are experiencing problems during GitLab package installation or have issues with package configuration please create an issue that includes the following:
+
 - Include the omnibus-gitlab version when discussing behavior: `dpkg-query -W
   gitlab` or `rpm -q gitlab`.
 - Be careful when pasting log output of `gitlab-ctl reconfigure`; Chef happily
   writes secrets to the log.
+#### For problems not related to package installation and configuration check ways to get help [at GitLab website.](https://about.gitlab.com/getting-help/)
+
 ## Merge request guidelines
 - Please add a CHANGELOG entry for your contribution