doc/Mainpage.dox - update the rfc implementation list

for consistency with the ReadMe.

Author: Allen Winter

doc/Mainpage.dox

@@ -8,7 +8,10 @@ and protocol data units. The iCalendar specification describes how
 calendar clients can communicate with calendar servers so users can
 store their calendar data and arrange meetings with other users.
 
-Libical implements RFC2445, RFC2446 and some of RFC2447.
+Libical implements RFC5545, RFC5546, RFC7529;
+the CalDav scheduling extensions in RFC6638;
+iCalendar extensions in RFC7986;
+plus the iCalendar iMIP protocol in RFC6047.
 
 @section license License