Syntax documentation rewrite for M-commands

Rewrote the syntax documentation for all commands starting with the
letter M.

docs/help/in/msg.in

@@ -1,15 +1,24 @@
 
+%9Syntax:%9
+
 @SYNTAX:msg@
 
-Sends a message to a nick or a channel. Usually this
-is used for sending private messages to other persons.
+%9Parameters:%9
 
-Examples:
+    -<server tag>:    The server tag the targets are on.
+    -channel:         Indicates that the target is a channel.
+    -nick:            Indicates that the target is a nickname.
 
-/MSG friend Hi, what's up?
+    The target nickname or channel and the message to send.
 
-/MSG #irssi Hello, is the new gtk-version out already?
-(This format is rarely needed.)
+%9Description:%9
 
-See also: CTCP
+    Sends a message to a nickname or channel.
+
+%9Examples:%9
+
+    /MSG mike Hi, what's up?
+    /MSG #irssi I am awesome :)
+
+%9See also:%9 ACTION, DCC, JOIN