Clean up JSDoc

[dylnslck]

Let's formalize how to write JSDoc. I can tell who is writing the documentation, which should not be the case. So, we need some rules.

Here are some tentative rules that I am proposing:

1. Don't use pronouns
2. Use complete sentences (the JSDoc is going to our actual API docs)
3. End param descriptions with a period
4. Encapsulate variables and functions with ticks
5. Use correct punctuation in JS comments in examples
6. Place JSDoc immediately above the function definition (helpers and imports go above)

Ultimately, we need to finalize this list and probably place it in a CONTRIBUTING.md or something.