Link to new extension type specification (#3270)

Author: parlough

working/1426-extension-types/feature-specification-inline-classes.md

@@ -2,8 +2,13 @@
 
 Author: [email protected]
 
-Status: Accepted.
+Status: Obsolete
 
+**This proposal is now obsolete. The mechanism has been renamed to
+_extension types_. Please see the [extension types specification][] for the
+accepted specification proposal.**
+
+[extension types specification]: https://github.com/dart-lang/language/blob/main/accepted/future-releases/extension-types/feature-specification.md
 
 ## Change Log
 

working/1426-extension-types/feature-specification-views.md

@@ -4,11 +4,11 @@ Author: [email protected]
 
 Status: Obsolete
 
-**This proposal is now obsolete. The mechanism has been renamed to _inline
-classes_. Please see the [inline classes specification][2] for the most recent proposed
-specification.**
+**This proposal is now obsolete. The mechanism has been renamed to
+_extension types_. Please see the [extension types specification][] for the
+accepted specification proposal.**
 
-[2]: https://github.com/dart-lang/language/blob/master/accepted/future-releases/inline-classes/feature-specification.md
+[extension types specification]: https://github.com/dart-lang/language/blob/main/accepted/future-releases/extension-types/feature-specification.md
 
 
 ## Change Log

working/1426-extension-types/feature-specification.md

@@ -2,7 +2,13 @@
 
 Author: [email protected]
 
-Status: Draft
+Status: Obsolete
+
+**This proposal is now obsolete. The mechanism has been renamed multiple times, and the
+current name is again _extension types_. Please see the new 
+[extension types specification][] for the accepted specification proposal.**
+
+[extension types specification]: https://github.com/dart-lang/language/blob/main/accepted/future-releases/extension-types/feature-specification.md
 
 
 ## Change Log