Moved the Gmail integration line into the list of available integrations.

doc/integration/README.md

@@ -8,11 +8,11 @@ See the documentation below for details on how to configure these services.
 - [LDAP](ldap.md) Set up sign in via LDAP
 - [OmniAuth](omniauth.md) Sign in via Twitter, GitHub, GitLab, and Google via OAuth.
 - [Slack](slack.md) Integrate with the Slack chat service
+- [OAuth2 provider](oauth_provider.md) OAuth2 application creation
+- [Gmail](gitlab_buttons_in_gmail.md) Adds GitLab actions to messages
 
 GitLab Enterprise Edition contains [advanced JIRA support](http://doc.gitlab.com/ee/integration/jira.html) and [advanced Jenkins support](http://doc.gitlab.com/ee/integration/jenkins.html).
 
-GitLab can also integrate with [Gmail](gitlab_buttons_in_gmail.md).
-
 ## Project services
 
 Integration with services such as Campfire, Flowdock, Gemnasium, HipChat, Pivotal Tracker, and Slack are available in the form of a Project Service.