Add checkout page for Instructor Trainers

Information on requirements for Instructor Trainer certification are listed in our handbook, but need to be included explicitly in the curriculum itself:

- Instructor Trainers agree to abide by the [Code of Conduct](http://www.datacarpentry.org/code-of-conduct/) in all communications and interactions with The Carpentries community.
- Trainees who are not previously certified Instructors will be asked to concurrently pursue [Instructor certification](https://carpentries.org/become-instructor/)
- Read [How Learning Works: Eight Research-Based Principles for Smart Teaching, 2nd Edition](https://www.wiley.com/en-us/How+Learning+Works%3A+Eight+Research-Based+Principles+for+Smart+Teaching%2C+2nd+Edition-p-9781119861690) by Marie K. Norman and discuss in book club format with Trainers-in-training. Preliminary reading schedule.
- Time commitment: 1 hour per week for 10 weeks meetings; can miss one meeting; ~10 hours reading
- Join Trainer meetings
- Time commitment: 1 hour per month; review minutes for missed meetings
- Shadow a teaching demonstration session (previously certified Instructors)
- Time commitment: 1 hour one time
- Shadow at least half a day of an online instructor training event (previously certified Instructors)
- Time commitment: 4 hours one time
- Agree to fulfill the duties outlined in the [Trainer Agreement](https://docs.carpentries.org/topic_folders/instructor_training/duties_agreement.html) for a period of 1 year.

Start by locating the Instructor Trainer curriculum section and compare it with the requirements in the handbook. Add the listed certification requirements, links, reading schedule, meeting commitments, shadowing expectations, and Trainer Agreement duty to the curriculum. Done means the curriculum explicitly contains all requested requirements and links.

Written by the indexing model from the issue text.