docs(sns): remove ignore from SnsSubscriptionMessage example

The doc example compiles as-is, so the ignore attribute is unnecessary.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: abhu85

lambda-events/src/event/sns/mod.rs

@@ -133,7 +133,7 @@ pub struct SnsMessage {
 ///
 /// # Example
 ///
-/// ```ignore
+/// ```
 /// use aws_lambda_events::event::sns::SnsSubscriptionMessage;
 ///
 /// fn handle_confirmation(msg: SnsSubscriptionMessage) {