fa2c2b50d8 doc: Extract net permissions doc (MarcoFalke)
Pull request description:
Moving the documentation of each flag form the already over-large init.cpp into the net permissions module should clean up the code a bit. Moreover, making the documentation available is also required for an (currently imaginary) `setnetpermissions` RPC.
ACKs for top commit:
Sjors:
re-utACK fa2c2b50d8
Tree-SHA512: c0a75facc9768913c28d2ffcdfaad8d60f7604d5584ee546adaf77d270563558d361aeaf354e49e349aca7e2e80814b27ffc24247e7b4f045c63cbdc079b449f