Merge branch 'docs/add-dot-com-only-badge' into 'master'

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See merge request gitlab-org/gitlab-ee!11401

doc/user/group/saml_sso/index.md

-# SAML SSO for GitLab.com Groups
+# SAML SSO for GitLab.com Groups **[SILVER ONLY]**
 
 > Introduced in [GitLab.com Silver](https://about.gitlab.com/pricing/) 11.0.