updated API doc to mention JSON RPC 2.0
updated API doc to mention JSON RPC 2.0

Reddcraft/reddcraftd,patricklodder/dogepartyd,metronotes-beta/metronotesd,CounterpartyXCP/counterparty-lib,F483/counterparty-lib,gotcha/testcounter,Ziftr/counterpartyd,Reddcraft/reddcraftd,monaparty/counterparty-lib,Dogeparty/dogepartyd,CounterpartyXCP/counterparty-lib,Ziftr/counterpartyd,Tetchain/tetchaind,coinwarp/dogeparty-lib,jarymoth/counterpartyd,Litetokens/litetokensd,Tetchain/tetchaind,monaparty/counterparty-lib,Dogeparty/dogepartyd,paytokens-beta/paytokensd,Bluejudy/bluejudyd,Czarparty/czarpartyd,tokenly/counterparty-lib,Bluejudy/bluejudyd,F483/counterparty-lib,Metronote/metronotesd-alpha,Paytokens/paytokensd,Peertokens/peertokensd,stefcrypto/counterparty-lib,ClearingHouse/clearinghoused,ClearingHouse/clearinghoused