specify what is meant by "invalidated" (#4291)

* specify what is meant by "invalidated"

Author: hf-kklein

xml/System.ComponentModel.DataAnnotations/IValidatableObject.xml

@@ -24,8 +24,8 @@
   </TypeForwardingChain>
   <Interfaces />
   <Docs>
-    <summary>Provides a way for an object to be invalidated.</summary>
-    <remarks>To be added.</remarks>
+    <summary>Provides a way for an object to be validated.</summary>
+    <remarks>Instances of types that implement this interface can be checked to determine if they are valid.</remarks>
   </Docs>
   <Members>
     <Member MemberName="Validate">