Prepare for broader use

We want the lesson to be used by other teachers. As authors, we know the material well, plus a lot of background, and we use this in our teaching. To fully prepare the material to also be a comfortable lesson for others, some things should be addressed:

- Scientific/academic language. We wrote this as a course for academics, but it can and should be used outside of that. We should remove references to science as the assumed profession of the learner.
- Workbench features. There are many specifically styled fences available for the Carpentries workbench lessons, that were not applied in the recent transition. This is an opportunity to do so.
- Instructor notes. We should add some of our teaching experiences to the materials, to the benefit of future instructors.
- Alt texts for images. Workbench tries to increase the accessibility of the Carpentries lessons, and it recommends using descriptive alt texts for images used. [More information here](https://carpentries.github.io/sandpaper-docs/episodes.html#figures).

As we go through the material, we can check off chapters here:
- [x] Index and setup #115
- [x] Introduction #115
- [x] Accessing Packages #115
- [ ] Getting Started
- [ ] Writing our own functions
- [ ] Licenses
- [ ] Testing
- [ ] Managing dependencies
- [ ] Documenting your package
- [ ] Data
- [ ] Vignettes