Polish contribution

Closes gh-5512

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/EnableAutoConfigurationImportSelector.java

@@ -143,7 +143,8 @@ public class EnableAutoConfigurationImportSelector
 		List<String> configurations = SpringFactoriesLoader.loadFactoryNames(
 				getSpringFactoriesLoaderFactoryClass(), getBeanClassLoader());
 		Assert.notEmpty(configurations,
-				"No auto configuration factories available. Please check your packaging to assure that the META-INF/spring.factories file is correct.");
+				"No auto configuration classes found in META-INF/spring.factories. If you" +
+						"are using a custom packaging, make sure that file is correct.");
 		return configurations;
 	}