Add option to sign-in with Okta

doc/development/chatops_on_gitlabcom.md

@@ -25,6 +25,7 @@ To request access to ChatOps on GitLab.com:
    - The same username you use on GitLab.com. You may have to choose a different
      username later.
    - Clicking the **Sign in with Google** button to sign in with your GitLab.com email address.
+   - Clicking the **Sign in with Okta** button to sign in with Okta.
 
 1. Confirm that your username in [Internal GitLab for Operations](https://ops.gitlab.net/)
    is the same as your username in [GitLab.com](https://gitlab.com/). If the usernames