remove coins not supported anymore (#372)

README.md

@@ -102,9 +102,6 @@ Each wallet and application then needs to implement this interface. In this repo
 | komodo (bitcoin) | ✅ | ✅ |
 | pivx (bitcoin) | ✅ | ✅ |
 | zencash (bitcoin) | ✅ | ✅ |
-| vertcoin (bitcoin) | ✅ | ✅ |
-| peercoin (bitcoin) | ✅ | ✅ |
-| viacoin (bitcoin) | ✅ | ✅ |
 | bitcoin_testnet (bitcoin) | ✅ | ✅ |
 | ethereum_ropsten (ethereum) | ✅ | ✅ |
 | ethereum_goerli (ethereum) | ✅ | ✅ |