Improve description of Endpoint exclude

See gh-13619

Author: 72MiguelGomes

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/endpoint/web/WebEndpointProperties.java

@@ -81,7 +81,7 @@ public static class Exposure {
 		private Set<String> include = new LinkedHashSet<>();
 
 		/**
-		 * Endpoint IDs that should be excluded.
+		 * Endpoint IDs that should be excluded or '*' for all.
 		 */
 		private Set<String> exclude = new LinkedHashSet<>();