updated alpha-README instructions to include adding RPC username/password to sidechain-manipulation.py
updated alpha-README instructions to include adding RPC username/password to sidechain-manipulation.py

gwillen/elements,pstratem/elements,fussl/elements,NunoEdgarGub1/elements,apoelstra/elements,NunoEdgarGub1/elements,truthcoin/blocksize-market,NunoEdgarGub1/elements,pstratem/elements,droark/elements,fussl/elements,apoelstra/elements,gwillen/elements,fussl/elements,fussl/elements,sipa/elements,droark/elements,pstratem/elements,droark/elements,NunoEdgarGub1/elements,aburan28/elements,sipa/elements,sipa/elements,truthcoin/blocksize-market,gwillen/elements,aburan28/elements,apoelstra/elements,truthcoin/blocksize-market,gwillen/elements,sipa/elements,pstratem/elements,aburan28/elements,fussl/elements,aburan28/elements,pstratem/elements,NunoEdgarGub1/elements,truthcoin/blocksize-market,NunoEdgarGub1/elements,droark/elements,gwillen/elements,droark/elements,apoelstra/elements,apoelstra/elements,sipa/elements,aburan28/elements,pstratem/elements,fussl/elements,apoelstra/elements,aburan28/elements,sipa/elements,truthcoin/blocksize-market,gwillen/elements,droark/elements,truthcoin/blocksize-market