rpc: define spec for RPC (#276)

* add rpc spec and support outline

* add json

* add more routes remove unneeded ones

* add rest of rpc endpoints

* add jsonrpc calls

* add more jsonrpc calls

* fix blockchain

* cleanup unused links and add links to repos

* Update spec/rpc/README.md

Co-authored-by: Callum Waters <cmwaters19@gmail.com>

* add missing param from consensus param

* Update spec/rpc/README.md

Co-authored-by: Callum Waters <cmwaters19@gmail.com>

* Update spec/rpc/README.md

Co-authored-by: Callum Waters <cmwaters19@gmail.com>

* fix cast and add doc to readme

Co-authored-by: Callum Waters <cmwaters19@gmail.com>
Co-authored-by: Marko Baricevic <markobaricevic@Fergalicious.local>

spec/README.md

@@ -42,6 +42,10 @@ please submit them to our [bug bounty](https://tendermint.com/security)!
 - [Mempool](./p2p/messages/mempool.md): gossip transactions so they get included in blocks
 - [Evidence](./p2p/messages/evidence.md): sending invalid evidence will stop the peer
 
+### RPC
+
+- [RPC SPEC](./rpc/README.md): Specification of the Tendermint remote procedure call interface.
+
 ### Software
 
 - [ABCI](./abci/README.md): Details about interactions between the