Remove extra line from AI Network docs
A small MR to address https://gitlab.slack.com/archives/C048Z2DHWGP/p1713429450255989, where in Adding more proxy and websocket info (!149486 - merged) • Suzanne Selhorn • 17.0 and Add Network Connectivity Requirements for GitLa... (!148996 - merged) • David O'Regan • 16.11, we added gitlab.com
but its not needed, this MR removes it.