How should we teach Carpentries history?

### How could the content be improved?

Inspired by #1798 that updates the history image from ending at 2020 to ending at 2025, but does not include that many new events, I wondered if we might have anything else in the last 5 years we would want to share. To answer that, I offer the following questions for discussion:

1. What are the key events or types of events in the Carpentries history we think are important for new instructors to know about and why?
1. What in the Carpentries history is important for a new member of the community to know about in order to best understand our values and structure?

There has been lots of discussion about the how we operate lesson being not the most engaging, but I think having a discussion about these two questions would help us think about how to keep this lesson both engaging and useful to the instructor training's overall goals.

### Which part of the content does your suggestion apply to?

https://carpentries.github.io/instructor-training/15-carpentries.html

Start with the lesson at 15-carpentries.html and review the current history content and its stated training goals. The issue asks for discussion about which events and values to include, but does not identify an agreed content change; done would require a decided scope and updated lesson plan or text.

Written by the indexing model from the issue text.