Update mediatypes.md

fix link to the subscription page of the [email protected] mailing list

the previous link seemed to point to a now deprecated mailing list.

Author: pchampin

editor/mediatypes.md

@@ -28,7 +28,7 @@ This procedure is based on [Media Type Specifications and Registration Procedure
    - Include a pointer to and a plaintext copy (not just an attachment) of the Media Type registration section in your email to [[email protected]](mailto:[email protected]).
    - Make sure you address and reply to comments and questions on [[email protected]](mailto:[email protected]). If you change the registration in your specification as a result of comments on ietf-type (or for any other reason), send the revised version to [[email protected]](mailto:[email protected]).
    - If you are registering an XML-based format, you may want to cc: [[email protected]](mailto:[email protected]).
-   - Note that you need to be [subscribed to the list](https://www.ietf.org/mailman/listinfo/ietf-types) to post to it.
+   - Note that you need to be [subscribed to the list](https://www.ietf.org/mailman/listinfo/media-types) to post to it.
    - To make it easier for your WG to track comments on the Media Type section, you may cross-post the comments list for your specification.
 3. In preparation for Candidate Recommendation: