Update service_endpoint example

Author: johnbatty

azure_devops_rust_api/examples/service_endpoint.rs

@@ -32,8 +32,8 @@ async fn main() -> Result<()> {
     // Display the returned service endpoints
     for endpoint in service_endpoints.iter() {
         println!(
-            "{:38} {:40} {}",
-            endpoint.id, endpoint.name, endpoint.description
+            "{:38} {:40} {:?}",
+            endpoint.id, endpoint.name, endpoint.description.as_deref().unwrap_or("")
         );
     }