📝 add docs for jsonrpc

Author: Zeroto521

.gitignore

@@ -43,4 +43,9 @@ coverage.xml
 
 # vscode
 .history
-.vscode
+.vscode
+
+
+# ppt
+*.ppt
+*.pptx

README.md

@@ -4,9 +4,27 @@
 
 Flow Launcher supports Python by JsonRPC.
 
-## JSON RPC
+## JSON-RPC
 
-<!-- A picture from wox.one -->
+> [JSON-RPC](https://en.wikipedia.org/wiki/JSON-RPC) is a remote procedure call protocol encoded in JSON.
+
+In Flow Launcher, we use JSON-RPC as a **local** procedure call protocol to bind Flow and other program languages.
+
+So we need to build a **common API** between Flow and Plugin.
+
+![JsonRPC](./assets/jsonrpc.png)
+
+### Example
+
+- `-->` denotes data sent to FLow.
+- `<--` denotes data coming from Flow.
+
+```json
+--> {"method": "query", "parameters": [""]}
+<-- {"Title": "title", "SubTitle": "sub title", "IconPath": "favicon.ico"}
+```
+
+<!-- TODO: try to add some other examples -->
 
 ## Installation
 
@@ -24,6 +42,8 @@ Flow Launcher supports Python by JsonRPC.
 >>> python setup.py install
 ```
 
+<!-- TODO: update Example Plugin (HellowWorldPython) for this plugin -->
+
 ### License
 
 This project is under the [MIT](./LICENSE) license.