Add specific contact for accessibility information - inst. app

Potentially add in one of these two places.
where is the most logical place to add this?
[Become an Instructor (carpentries.org)](https://carpentries.org/become-instructor/)?
[For Current Carpentries Instructors — The Carpentries Handbook documentation](https://docs.carpentries.org/topic_folders/for_instructors/current_instructors.html)

Review the two linked pages: Become an Instructor and the Current Carpentries Instructors handbook documentation. First determine which page is the logical location for accessibility information and what contact details should be included. Done means the chosen page identifies a specific contact for accessibility information.

Written by the indexing model from the issue text.