update async-graphql example

graphql/async-graphql/README.md

@@ -0,0 +1,38 @@
+## GraphQL using `async-graphql`
+
+> Getting started using [async-graphql](https://github.com/async-graphql/async-graphql) with Actix Web.
+
+## Usage
+
+```bash
+cd graphql/graphql-demo
+cargo run
+```
+
+## Endpoints
+
+```
+GET/POST  http://localhost:8080/graphql   GraphQL endpoint
+GET       http://localhost:8080/graphiql  GraphQL playground UI
+```
+
+## Query Examples
+
+```graphql
+{
+  humans {
+    edges {
+      node {
+        id
+        name
+        friends {
+          id
+          name
+        }
+        appearsIn
+        homePlanet
+      }
+    }
+  }
+}
+```