Doc: Added IMAP RFC link
Doc: Added IMAP RFC link

buildscientist/greenmail,chriswhite199/greenmail,greenmail-mail-test/greenmail,chriswhite199/greenmail,rucek/greenmail,buildscientist/greenmail,marcelmay/greenmail,rucek/greenmail,marcelmay/greenmail,chriswhite199/greenmail,jianglili007/greenmail,Chessray/greenmail,rucek/greenmail,rucek/greenmail,marcelmay/greenmail,jianglili007/greenmail,jianglili007/greenmail,jianglili007/greenmail,buildscientist/greenmail,marcelmay/greenmail,Chessray/greenmail,chriswhite199/greenmail,Chessray/greenmail,greenmail-mail-test/greenmail,Chessray/greenmail,buildscientist/greenmail,buildscientist/greenmail,chriswhite199/greenmail,greenmail-mail-test/greenmail,marcelmay/greenmail