Fix typo

Author: TheRealAyCe

net.sf.eclipsecs.checkstyle/metadata/com/puppycrawl/tools/checkstyle/checks/design/checkstyle-metadata.properties

@@ -1,6 +1,6 @@
 Design.group = Class Design
 
-DesignForExtension.desc = Checks that classes are designed for extension. More specifically, it enforces a programming style where superclasses provide empty "hooks" that can be implemented by subclasses.<br/>\r\nThe exact rule is that nonprivate, nonstatic methods of classes that can be subclassed must either be\r\n<ul>\r\n<li>abstract or</li>\r\n<li>final or</li>\r\n<li>have an empty implementation</li>\r\n</ul>\r\nRationale: This API design style protects superclasses against beeing broken by subclasses. The downside is that subclasses are limited in their flexibility, in particular they cannot prevent execution of code in the superclass, but that also means that subclasses cannot corrupt the state of the superclass by forgetting to call the super method.
+DesignForExtension.desc = Checks that classes are designed for extension. More specifically, it enforces a programming style where superclasses provide empty "hooks" that can be implemented by subclasses.<br/>\r\nThe exact rule is that nonprivate, nonstatic methods of classes that can be subclassed must either be\r\n<ul>\r\n<li>abstract or</li>\r\n<li>final or</li>\r\n<li>have an empty implementation</li>\r\n</ul>\r\nRationale: This API design style protects superclasses against being broken by subclasses. The downside is that subclasses are limited in their flexibility, in particular they cannot prevent execution of code in the superclass, but that also means that subclasses cannot corrupt the state of the superclass by forgetting to call the super method.
 DesignForExtension.name = Design For Extension
 DesignForExtension.ignoredAnnotations = Annotations which allow the check to skip the method from validation.
 
@@ -38,4 +38,4 @@ VisibilityModifier.immutableClassCanonicalNames = immutable classes canonical na
 VisibilityModifier.ignoreAnnotationCanonicalNames = ignore annotations canonical names
 
 OneTopLevelClass.name = One Top Level Class
-OneTopLevelClass.desc = Checks that each top-level class, interface or enum resides in a source file of its own. Official description of a 'top-level' term:7.6. Top Level Type Declarations. If file doesn't contains public class, enum or interface, top-level type is the first type in file.
+OneTopLevelClass.desc = Checks that each top-level class, interface or enum resides in a source file of its own. Official description of a 'top-level' term:7.6. Top Level Type Declarations. If file doesn't contains public class, enum or interface, top-level type is the first type in file.