adding input/output to readme

Author: BaseMax

README.md

@@ -21,6 +21,8 @@ Open `http://localhost:8080/` at your browser and use.
 
 ## Example
 
+#### Input
+
 ```graphql
 {
   echo(message: "Hello World")
@@ -32,6 +34,21 @@ Open `http://localhost:8080/` at your browser and use.
 }
 ```
 
+#### Output
+
+```json
+{
+  "data": {
+    "echo": "Welcome, Dear Hello World",
+    "sum": 12,
+    "s2": 3,
+    "s3": 62,
+    "s4": 52,
+    "s5": 102
+  }
+}
+```
+
 ## GraphQL Playground
 
 Installing at arch: `yay graphql-playground-electron`