Remove hard copies of RFCs and I-D from BIND repository
Remove hard copies of RFCs and I-D from BIND repository, the authoritative source is IETF, and our copies doesn't reflect any errata and other updates to the repository.
If anyone feels strongly about it, it could be turned into separate git repository, it doesn't have to be part of bind9.git and especially there's no reason for it to be part of BIND release tarballs.