matrix/m.room.power_levels: add m.room.pinned_events

This reverts commit 907cff616f.

matrix/m.room.power_levels/README.md

@@ -34,10 +34,11 @@ This is not the Element/Synapse default as that would be pointless to list.
 	"events": {
 		"im.vector.modular.widgets": 50,
 		"m.room.avatar": 50,
-		"m.room.canonical_alias": 50,
+		"m.room.canonical_alias": 13,
 		"m.room.encryption": 100,
 		"m.room.history_visibility": 99,
 		"m.room.name": 50,
+		"m.room.pinned_events": 25,
 		"m.room.power_levels": 50,
 		"m.room.retention": 100,
 		"m.room.server_acl": 100,
@@ -58,16 +59,26 @@ This is not the Element/Synapse default as that would be pointless to list.
 }
 ```
 
+* `m.room.history_visibility` is lowered to 99 as it's a less permanent action than
+  many of the others. I am not sure on my initial logic, but it's documented in
+  PPFI repo as PL100 vs PL99.
 * `m.room.power_levels` is set to `50` so moderators can raise others to moderators
   for example matrix-appservice-irc, which I would then give PL51 for ops syncing.
   On matrix side immune mods, could be PL52.
 * invite commonly defaults to `50`, but I haven't seen abuse through it
 * PL25, half-moderator is introduced (inspired from Ergo/IRC halfop), with powers to:
-  change room topic and kick users (but not ban)
+  change room topic, pinned messages and kick users (but not ban)
   * In Ergo it would also allow joining the room when it's invite-only (but Matrix
     has separate `m.room.join_rules` so maybe it could be used e.g. in an association
     where a secretary/someone unwilling to be a full moderator wants to update
     room topic for next meeting time or update a version number? :shrug:
+* PL13 gets access to change main alias and add/remove published room aliases alongside
+  (at least on Synapse) [un/publish the room in the room directory](https://github.com/vector-im/element-web/issues/13835).
+  * This can be used with e.g. [altalias maubot plugin](https://matrix.org/blog/2020/06/19/this-week-in-matrix-2020-06-19#alt-alias-maubot-plugin).
+    I don't care about room directory or the main alias as it doesn't affect ctrl-k that much anyway,
+    rooms are generally discovered through Spaces and I use Matrix URI scheme
+    which takes room internal ID and servers to find it from instead of caring about
+    the alias. Most importantly **don't give permissions to entirely untrusted users.**
 
 ### Medium version
 
@@ -77,10 +88,11 @@ This is not the Element/Synapse default as that would be pointless to list.
 	"events": {
 		"im.vector.modular.widgets": 50,
 		"m.room.avatar": 50,
-		"m.room.canonical_alias": 50,
+		"m.room.canonical_alias": 13,
 		"m.room.encryption": 100,
 		"m.room.history_visibility": 99,
 		"m.room.name": 50,
+		"m.room.pinned_events": 25,
 		"m.room.power_levels": 50,
 		"m.room.retention": 100,
 		"m.room.server_acl": 100,
@@ -117,7 +129,7 @@ This is not the Element/Synapse default as that would be pointless to list.
 		"m.room.encryption": 100,
 		"m.room.history_visibility": 100,
 		"m.room.name": 100,
-		"m.room.pinned_events": 50,
+		"m.room.pinned_events": 100,
 		"m.room.power_levels": 100,
 		"m.room.redaction": 0,
 		"m.room.retention": 100,