Add warning text to the `server_domain` pref

• Add warning text to the server_domain pref

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• [DOC] server_domain: Add warning text to the server_domain pref as it is dangerous and causes support issues (would be better to remove it entirely imho)

See merge request !5150 (merged)

(cherry picked from commit d5049254)

c8c39ede [DOC] server_domain: Add warning text to the server_domain pref as it is...

Co-authored-by: Jonny Bradley jmail@nospaces.net