Document the standards IOV-Core implements in the Readme

[Isabello]

We have a variety of standards implemented from https://github.com/bitcoin/bips . We should list these in the Readme or atleast document them somewhere in the repo for those wondering about compatibility.

I believe this includes the following list.

BIP32: https://github.com/bitcoin/bips/blob/master/bip-0032.mediawiki BIP39: https://github.com/bitcoin/bips/blob/master/bip-0039.mediawiki BIP43: https://github.com/bitcoin/bips/blob/master/bip-0043.mediawiki BIP44: https://github.com/bitcoin/bips/blob/master/bip-0044.mediawiki SLIP0010: https://github.com/satoshilabs/slips/blob/master/slip-0010.md