Suggestion for expert awareness gap discussion

A recent article in the Verge, ["File Not Found"](https://www.theverge.com/22684730/students-file-folder-directory-structure-education-gen-z) has been generating [a lot of discussion](https://swcarpentry.slack.com/archives/C03LE48BA/p1632313672016700) about teaching file systems to "Gen-Z".

It includes a quote that I think would be a good addition to the ["Expertise and Instruction" episode of Instructor Training](https://carpentries.github.io/instructor-training/03-expertise/index.html).

> Directory structure isn’t just unintuitive to students — it’s so intuitive to professors that they have difficulty figuring out how to explain it.

This quote and a link to the article could perhaps be added as a callout near the end of [the first section](https://carpentries.github.io/instructor-training/03-expertise/index.html#expertise-and-teaching) or added to [the existing discussion on expert awareness gaps there](https://carpentries.github.io/instructor-training/03-expertise/index.html#awareness-gaps--optional).

Start with the linked “Expertise and Instruction” episode, especially the “expertise and teaching” and “awareness gaps” sections. Review the linked Verge article for context, then add the quoted discussion and article link as a callout near the first section or within the existing awareness-gaps discussion. Done means the quote and source are clearly included in the episode.

Written by the indexing model from the issue text.