Document the Configure ad-hoc commands

doc/biboumi.1.md

@@ -401,6 +401,9 @@ Affiliation set to `owner`
 ### Ad-hoc commands
 
 Biboumi supports a few ad-hoc commands, as described in the XEP 0050.
+Different ad-hoc commands are available for each JID type.
+
+#### On the gateway itself (e.g on the JID biboumi.example.com):
 
   - ping: Just respond “pong”
 
@@ -421,6 +424,20 @@ Biboumi supports a few ad-hoc commands, as described in the XEP 0050.
     with an XMPP message.  The administrator can disconnect any user, while
     the other users can only disconnect themselves.
 
+#### On a server JID (e.g on the JID chat.freenode.org@biboumi.example.com)
+
+  - Configure: Lets each user configure some options that applies to the
+    concerned IRC server.
+
+#### On a channel JID (e.g on the JID #test%chat.freenode.org@biboumi.example.com)
+
+  - Configure: Lets each user configure some options that applies to the
+    concerned IRC channel.  Some of these options, if not configured for a
+    specific channel, defaults to the value configured at the IRC server
+    level.  For example the encoding can be specified for both the channel
+    and the server.  If an encoding is not specified for a channel, the
+    encoding configured in the server applies.
+
 ### Raw IRC messages
 
 Biboumi tries to support as many IRC features as possible, but doesn’t