add `IRC convert (RC rc);` to IRCConverter doc
add `IRC convert (RC rc);` to IRCConverter doc

[ci skip]

barspi/jPOS,jpos/jPOS,barspi/jPOS,alcarraz/jPOS,jpos/jPOS,alcarraz/jPOS,barspi/jPOS,alcarraz/jPOS,jpos/jPOS