Standardizing the 100-word preview summaries displayed in study grid

@becky-gilbert is already working on this.

Since May 17, 2023.

Researchers have many different approaches to writing the "under 100 words" preview summary that appears on the listing page of available studies. That is a field that was added more recently than the "short description" and "purpose" fields, and we have not updated instructions, self-review checklists, or admin review to reflect it.

Thus, researchers have chosen a lot of different approaches. For example, they have different mixes of "what" and "purpose". And some just say "This study will take place on a video call, live with a researcher!" and nothing more. And there are many more variations!

For some useful standardization, one idea is that we require the following template (exceptions allowable for good reasons):
[optional detail about study delivery] + [major detail about what happens] + [optional major detail about purpose]

Below is what it would look like for a few examples. In each example, both optional bits are included, but some studies might not have anything to include in the first bit (especially if it was just a "standard" internal study):

- "In this scheduled video chat with a researcher, your baby will look at pictures of orange and blue shapes, and we will learn how babies understand numbers."
- "In this study that requires your child to have paper and crayons, your child will draw pictures of imaginary objects, and we will learn about children's artistic preferences."
- In this study that involves at least one scheduled session and might include up to four more, your child will chat with a researcher about science demonstrations, and we will learn about children's memory abilities

This should be updated in multiple places:

- Admin review document (Mark can do this, once we decide on content, such as the above suggestion)
- The read the docs entry for "Preview summary" [here](https://lookit.readthedocs.io/en/develop/researchers-set-study-fields.html)
- The [self-review checkist](https://lookit.readthedocs.io/en/develop/community-study-review-checklists-self.html?highlight=checklist) should mention this