message: update JSON-RPC doc
  minor changes to make style consistent with dev docs
  Closes:
diff: @@ -16,7 +16,7 @@ List of released stable methods (unless specifically mentioned, all parameters a
  * [get_currencies](docs/method_get_currencies.md)() -> List<[CurrencyInfo](docs/type_currency_info.md)>
  -> For implementing a client, please checkout our [Client Implementation Guide](docs/client_implementation_guide.md)
  +> To implement a client, please checkout our [Client Implementation Guide](docs/client_implementation_guide.md).
  ## Official Client SDKs
  @@ -27,17 +27,17 @@ List of released stable methods (unless specifically mentioned, all parameters a
  JSON-RPC is a stateless, light-weight remote procedure call (RPC) protocol. Refer to the [JSON-RPC Specification](https://www.jsonrpc.org/specification) for further details.
  -### Libra Extensions
  +### Libra extensions
  -JSON-RPC response object is extended with the following fields:
  +The JSON-RPC response object is extended with the following fields:
  -| field | type | meaning |
  +| Field | Type | Meaning |
  |----------------------------|----------------|----------------------------------------------|
  | libra_chain_id | unsigned int8 | network chain id, e.g. testnet chain id is 2 |
  -| libra_ledger_version | unsigned int64 | server side latest ledger version number |
  -| libra_ledger_timestampusec | unsigned int64 | server side latest ledger timestamp microseconds |
  +| libra_ledger_version | unsigned int64 | server-side latest ledger version number |
  +| libra_ledger_timestampusec | unsigned int64 | server-side latest ledger timestamp microseconds |
  -You can use these information to verify liveness / status of nodes in the network: if the timestamp or version is old (from the past), it means that the request hit a full node that is not up-to-date.
  +You can use this information to verify liveness / status of nodes in the network: if the timestamp or version is old (from the past), it means that the request hit a full node that is not up-to-date.
  #### Example:
  @@ -60,15 +60,15 @@ You can use these information to verify liveness / status of nodes in the networ
  ### Batched requests
  -The JSON-RPC protocol allows requests to be batched. An arbitrary number of requests (max 20 by default) can be combined into a single batch and submitted to the server. These requests will be processed together under a single request context.
  +The JSON-RPC protocol allows requests to be batched. An arbitrary number of requests (maximum 20 by default) can be combined into a single batch and submitted to the server. These requests will be processed together under a single request context.
  ### Errors
  -If errors occur during a request, they are returned in an error object, as defined in: [https://www.jsonrpc.org/specification#error_object](https://www.jsonrpc.org/specification#error_object)
  -For any invalid request or parameters request, standard Error code and message with human readable information will be returned.
  +If errors occur during a request, they are returned in an error object, as defined in: [https://www.jsonrpc.org/specification#error_object](https://www.jsonrpc.org/specification#error_object).
  +For any invalid request or parameters request, a standard error code and message with human readable information will be returned.
  -| code | meaning |
  +| Code | Meaning |
  |--------|-----------------------------------------|
  | -32600 | standard invalid request error |
  | -32601 | method not found or not specified |
  