add typedef and resolvers in apollo server nodejs doc (#1418)

Signed-off-by: Bhavya Dhiman <[email protected]>

Author: bhavya3024

src/code/language-support/javascript/server/apollo-server.md

@@ -17,6 +17,19 @@ Then run `node server.js` with this code in `server.js`:
 ```js
 import { ApolloServer } from "@apollo/server"
 import { startStandaloneServer } from "@apollo/server/standalone"
+import { buildSchema } from "graphql"
+
+const schema = buildSchema(`
+   type Query {
+      hello: String
+   }
+`)
+
+const resolvers = {
+  Query: {
+    hello: () => "Hello World!",
+  },
+}
 
 const server = new ApolloServer({
   typeDefs,