Fix websocket path in README.
Fix websocket path in README.

btcsuite/btcwallet,jrick/dcrwallet,Roasbeef/btcwallet,decred/dcrwallet,decred/dcrwallet,Stash-Crypto/btcwallet,Roasbeef/btcwallet,synrg-labs/btcwallet,Stash-Crypto/btcwallet,synrg-labs/btcwallet,btcsuite/btcwallet,jrick/dcrwallet,jrick/btcwallet,jrick/btcwallet