Add documentations for new APIs

JSON-RPC.md

@@ -21,6 +21,10 @@ JSON-RPC APIs are APIs provided by running a JeChain RPC server. They can be use
     * Use case: Get hash and nonce from the latest block.
     * Reply body: `{ success: true, payload: { hash: <hash>, nonce: <nonce> } }`
 
+* `/mining`:
+    * Use case: Check on whether client is mining or not.
+    * Reply body: `{ success: true, payload: { mining: true | false } }`
+
 ### POST
 
 * `/get_blockByHash`:
@@ -89,6 +93,15 @@ JSON-RPC APIs are APIs provided by running a JeChain RPC server. They can be use
             * Status: 400
             * Body: `{ success: false, payload: null, error: { message: "Invalid request." } }`
 
+* `/get_storage`:
+    * Use case: Get the storage object from address.
+    * Request body: `{ params: { address: <address> } }`
+    * Reply body: `{ success: true, payload: { storage: <storage_object> } }`
+    * Error body:
+        * Invalid request (not enough params):
+            * Status: 400
+            * Body: `{ success: false, payload: null, error: { message: "Invalid request." } }`
+
 * `/sendTransaction`:
     * Use case: Send transaction.
     * Request body: `{ params: { transaction: <transaction_object> } }`