Fix link to DataAnnotations source (#17979)

* Fix link to DataAnnotations source

* Update aspnetcore/mvc/models/validation.md

Co-Authored-By: Scott Addie <10702007+scottaddie@users.noreply.github.com>

Co-authored-by: Scott Addie <10702007+scottaddie@users.noreply.github.com>

Author: serpent5

aspnetcore/mvc/models/validation.md

@@ -73,7 +73,7 @@ Internally, the attributes call `String.Format` with a placeholder for the field
 
 When applied to a `Name` property, the error message created by the preceding code would be "Name length must be between 6 and 8.".
 
-To find out which parameters are passed to `String.Format` for a particular attribute's error message, see the [DataAnnotations source code](https://github.com/dotnet/corefx/tree/master/src/System.ComponentModel.Annotations/src/System/ComponentModel/DataAnnotations).
+To find out which parameters are passed to `String.Format` for a particular attribute's error message, see the [DataAnnotations source code](https://github.com/dotnet/runtime/tree/master/src/libraries/System.ComponentModel.Annotations/src/System/ComponentModel/DataAnnotations).
 
 ## [Required] attribute