Fix typos.

Fix typos.
(Getting started with rcirc): New calling convention for M-x irc.
Mention #rcirc.  Removed channel tracking.
(Configuration): Changed the names of all variables that got changed
recently, eg. rcirc-server to rcirc-default-server.  Added
documentation for rcirc-authinfo, some background for Bitlbee, and
rcirc-track-minor-mode.
(Scrolling conservatively): Fixed the xref from Auto Scrolling to just
Scrolling.
(Reconnecting after you have lost the connection): Fixed example code
to match code changes.