Minor improvements to the release process
Minor improvements to the release process

Instruct people to "git fetch" so that if this is their 2nd+ gitian build they will have a fresh bitcoin repo.
Instruct people to add all the known pgp keys to their keyring so that gverify will print more useful info.

bitjson/hivemind,bitcoin-hivemind/hivemind,bitjson/hivemind,bitcoin-hivemind/hivemind,bitjson/hivemind,bitcoin-hivemind/hivemind,bitjson/hivemind,bitcoin-hivemind/hivemind,bitjson/hivemind,bitcoin-hivemind/hivemind,bitjson/hivemind,bitjson/hivemind,bitcoin-hivemind/hivemind,bitcoin-hivemind/hivemind