Syntax: %bSET <channel> COMMENT <comment|->%b

Sets the channel comment line to <comment>.  When users
perform an %bINFO%b on the channel, they will be informed
of the channel's comment.  To clear the comment use a "-"
as the parameter.

Examples:
         %b/msg %C SET <channel> COMMENT John's place%b
           Sets the comment to "John's place" on <channel>

         %b/msg %C SET <channel> COMMENT -
           Clears the comment on <channel>
