Clarify the meaning of "public rooms" for policy lists (#2107)

changelogs/client_server/newsfragments/2107.clarification

@@ -0,0 +1 @@
+"Public" rooms have no specific meaning with respect to moderation policy lists.

content/client-server-api/modules/moderation_policies.md

@@ -18,8 +18,9 @@ the entity making the decisions on filtering is best positioned to
 interpret the rules how it sees fit.
 
 Moderation policy lists are stored as room state events. There are no
-restrictions on how the rooms can be configured (they could be public,
+restrictions on how the rooms can be configured in terms of
-private, encrypted, etc).
+[join rules](#mroomjoin_rules), [history visibility](#room-history-visibility),
+encryption, etc.
 
 There are currently 3 kinds of entities which can be affected by rules:
 `user`, `server`, and `room`. All 3 are described with