Update OpenAPIReturnsContainer.java

Author: SentryMan

http-api/src/main/java/io/avaje/http/api/OpenAPIReturnsContainer.java

@@ -6,6 +6,7 @@
 import java.lang.annotation.Retention;
 import java.lang.annotation.Target;
 
+/** a container for the OpenAPIReturns annotation to make it repeatable */
 @Target(value = METHOD)
 @Retention(value = RUNTIME)
 public @interface OpenAPIReturnsContainer {