Standardize formatting in Suggested Lesson Tables

Clean up minor inconsistencies in [suggested lessons](https://carpentries.github.io/instructor-training/demo_lessons/index.html) including:
* consistent phrasing, capitalization, and punctuation for explanations (e.g. "none" vs. "No episodes"; "Avoid all episodes.", etc)
* consistent language use in the Spanish lessons (one note in English, rest in Spanish)
* Consistent decision to use unordered lists (`*`) or line breaks (`
`) to separate rows in good/avoid lessons cells (ex: SC R Gapminder uses rows while most use lists)

Additionally, I suggest we consider using lists (`*`) in all good/avoid lesson cells, even when it's just one item for consistency.

Start from the linked Suggested Lessons page and locate the source for its lesson tables. Review the explanations, Spanish notes, and good/avoid lesson cells for the stated wording, language, punctuation, and separator inconsistencies. Done means the tables follow one consistent convention and the resulting page has no remaining inconsistencies.

Written by the indexing model from the issue text.