Add options to disable setting profile info for prevent changes. (#7053)

docs/sample_config.yaml

@@ -1057,6 +1057,19 @@ account_threepid_delegates:
     #email: https://example.com     # Delegate email sending to example.com
     #msisdn: http://localhost:8090  # Delegate SMS sending to this local process
 
+# If disabled, don't let users set their own display names/avatars
+# (unless they are a server admin) other than for the very first time.
+# Useful when provisioning users based on the contents of a 3rd party
+# directory and to avoid ambiguities.
+#
+#enable_set_displayname: true
+#enable_set_avatar_url: true
+
+# If false, stop users from trying to change the 3PIDs associated with
+# their accounts.
+#
+#enable_3pid_changes: true
+
 # Users who register on this homeserver will automatically be joined
 # to these rooms
 #