Merge branch 'docs-distribution-spamcheck-ee-free' into 'master'

Docs: Spamcheck is available in the Free tier, with EE requirement

See merge request gitlab-org/gitlab!81751

doc/user/admin_area/reporting/spamcheck.md

@@ -12,6 +12,8 @@ info: To determine the technical writer assigned to the Stage/Group associated w
 developed by GitLab originally to combat rising amount of spam in GitLab.com,
 and later made public to be used in self-managed GitLab instances.
 
+Spamcheck [contains obfuscated, non-free code](https://gitlab.com/gitlab-org/omnibus-gitlab/-/issues/6259#note_726605397), which is only available in GitLab Enterprise Edition. You can [migrate from GitLab Community Edition](../../../update/package/convert_to_ee.md), and use the Free tier. 
+
 ## Enable Spamcheck
 
 Spamcheck is only available for package-based installations: