docs(README): add BIP44 & WIF examples

[coolaj86]

Removed this info, which is still valuable info:

To convert to Base58Check and WIF addresses:

var Base58check = require('base58check');

var addr = Base58Check.encode(childkey.pubKeyHash, prefix = '00');

var compressed = '01';
var wif = Base58Check.encode(
  childkey.privateKey.toString('hex') + compressed,
  prefix = '80',
);

[coolaj86]

Good catch. Fixed and removed.