Remove the extra RFC and I-D copies from BIND source distribution
Copied from here: https://bugs.isc.org/Ticket/Display.html?id=46211
@marka Argues that it's handy to have a copies, but:
- We can have an extra repository and not distribute them in the BIND 9 source code
- We are missing erratas anyway
We should just make a list with the RFCs and I-D and explicitly declare which standards (and at what levels) we support.