Update getting-started.mdx

Author: Shubhdeep12

website/pages/docs/getting-started.mdx

@@ -58,7 +58,7 @@ graphql({
 </Tabs.Tab>
 <Tabs.Tab>
 ```javascript
-const { graphql, GraphQLSchema, GraphQLObjectType } = require('graphql');
+const { graphql, GraphQLSchema, GraphQLObjectType, GraphQLString } = require('graphql');
 
 // Construct a schema
 const schema = new GraphQLSchema({