Text content updates based on curator discussion

This PR contains many text updates to address issues with text length, consistency, and other issues discussed with the curators. Ideally I would've broken this up into a few more targeted commits, rather than one big commit, but it was more effective for the discussion for me to make live updates to the code (so the curators could see the effects of things I was suggesting) and there were too many changes for me to track of and update the code more systematically later.

Also, although almost all the updates are to the yaml files, I did comment out a line in a couple of the HTML includes files. It probably would be cleaner to delete these lines rather than commenting them out, but until the curators can see the results of all of these changes, it felt safer to comment them out so it would be more clear how to revert the changes if we need to.

sul-dlss / wallscreens

Text content updates based on curator discussion #242