renamed msrp_relay_address to msrp_relay in scripts/README.txt

darcs-hash:20081128130112-b2873-b8a576bff4d625884435f5dceedac41de16502fb
added info about msrplib and msrp scripts to the changelog

darcs-hash:20081128131229-b2873-38af2474d64804b868da428de8f9639a7441e0df