Add GraphQL API usage and integration details to README

Added documentation for the GraphQL API, including endpoints, example queries, and integration benefits. This provides guidance for developers on how to use and integrate the new GraphQL functionality alongside the existing REST API.

Author: alegauss

README.adoc

@@ -173,6 +173,54 @@ curl -X POST "http://localhost:2700/api/sn/MySite" \
     }]
   }'
 ----
+=== GraphQL API Example
+
+=== API Endpoints
+
+- **GraphQL API**: `POST /graphql`
+- **GraphiQL Interface**: `GET /graphiql`
+
+=== Example Usage
+
+[source,graphql]
+----
+query {
+  siteSearch(
+    siteName: "your-site-name"
+    searchParams: {
+      q: "technology"
+      rows: 10
+      p: 1
+      sort: "relevance"
+    }
+    locale: "en"
+  ) {
+    queryContext {
+      count
+      responseTime
+    }
+    results {
+      numFound
+      document {
+        fields {
+          title
+          text
+          url
+        }
+      }
+    }
+  }
+}
+----
+
+=== Integration Benefits
+
+1. **Type Safety**: Strong typing prevents runtime errors
+2. **Flexible Queries**: Clients can request exactly the data they need
+3. **Single Endpoint**: All search operations through one GraphQL endpoint
+4. **Backward Compatibility**: Existing REST API remains unchanged
+5. **Interactive Development**: GraphiQL interface for query development
+6. **Consistent Results**: Uses same search engine and processing as REST API
 
 == 🛠️ Development Setup