mod_mix_pam: Update README

mod_mix_pam/README.markdown

@@ -1,4 +1,47 @@
-This module implements MIX-PAM, which is needed for MIX clients to function.
+---
-Note that this module does not implement any other MIX protocol besides MIX-PAM.
+labels:
+- 'Stage-Alpha'
+summary: 'XEP-0405: Participant Server Requirements'
+...
 
-To use this module, just enable it.
+Introduction
+============
+
+This module implements [XEP-0405: Participant Server Requirements](https://xmpp.org/extensions/xep-0405.html).
+It allows MIX clients to join and leave MIX channels on other servers, while
+also distributing messages to those clients.
+
+Install and enable it like any other module. It has no configuration.
+
+Compatibility
+=============
+
+This module currently requires the following patch to be applied to
+mod_roster.lua:
+
+``` {.patch}
+# HG changeset patch
+# User Alexander "PapaTutuWawa" <papatutuwawa@polynom.me>
+# Date 1620730362 -7200
+#      Tue May 11 12:52:42 2021 +0200
+# Node ID 8ea24ca499db1865b754e5c5dffcdc84a9ce7737
+# Parent  30feeb4d9d0b51f968c16b205137c114e62047b9
+mod_roster: Add event for roster get queries
+
+diff -r 30feeb4d9d0b -r 8ea24ca499db plugins/mod_roster.lua
+--- a/plugins/mod_roster.lua	Fri May 07 16:47:58 2021 +0200
++++ b/plugins/mod_roster.lua	Tue May 11 12:52:42 2021 +0200
+@@ -57,6 +57,7 @@
+ 			end
+ 			roster.tags[1].attr.ver = server_ver;
+ 		end
++		module:fire_event("roster-get", { session = session, stanza = stanza, reply = roster });
+ 		session.send(roster);
+ 		session.interested = true; -- resource is interested in roster updates
+ 	else -- stanza.attr.type == "set"
+```
+
+  ----- ----------------------
+  trunk Untested (needs patch)
+  0.11  Works (needs patch)
+  ----- ----------------------