Add step by step tutorial to setting up ENS

[estebanabaroa]

TODO: Add step by step documentation to set up ENS. Something like

you have to add the "text record" "subplebbit-address" to https://legacy.ens.domains/name/yourname.eth

you need to have some ethereum, buy a .eth domain, then set the name record, it takes several .eth transactions, maybe $20 in gas total depending on how high fees are

it's easy to do if you've used ethereum before, but hard if you havent

then you need to edit the address of your subplebbit in the cli to yourname.eth, we need a step by step tutorial in the CLI, there's a lot of steps