Update doc with rpc statuses
@@ -23,6 +23,37 @@ RPC-API consists of several modules:
All communications with rpc api are going through `/ POST` or `WS` connection.
+======================
+JSON RPC error codes
+======================
+Base JSON RPC errors taken from spec https://www.jsonrpc.org/specification, but also has own custom codes.
+
++------------+----------------------------------+------------------------------------------------------+
+| Code | Possible Return message | Description |
++============+==================================+======================================================+
+| -32700 | Parse error | Invalid JSON was received by the server. An error |
+| | | occurred on the server while parsing the JSON text |
++------------+----------------------------------+------------------------------------------------------+
+| -32600 | Invalid Request | The JSON sent is not a valid Request object |
++------------+----------------------------------+------------------------------------------------------+
+| -32601 | Method not found | The method does not exist / is not available. |
++------------+----------------------------------+------------------------------------------------------+
+| -32602 | Invalid params | Invalid method parameter(s) |
++------------+----------------------------------+------------------------------------------------------+
+| -32603 | Internal error | Internal JSON-RPC error |
++------------+----------------------------------+------------------------------------------------------+
+| -32001 | Resource not found | Some resource by identifier not found on chain |
++------------+----------------------------------+------------------------------------------------------+
+| -32002 | Validator is not ready yet | Validator is not prepared for handling of requests |
++------------+----------------------------------+------------------------------------------------------+
+| -32003 | Invalid or missing header | Wrong header for validator request |
++------------+----------------------------------+------------------------------------------------------+
+| -32004 | Invalid or missing resource id | Wrong id for some resource |
++------------+----------------------------------+------------------------------------------------------+
+| -32005 | Invalid limit count | Wrong limit count for resource |
++------------+----------------------------------+------------------------------------------------------+
+
+
======================
JSON RPC API Reference
======================
