quick pass at the docs

[beaugunderson]

hey @rachelnicole! super quick pass before bed--can look more in-depth tomorrow.

the specific reason not to use links with the link text of 'here' is that they're not great for people using screen readers.

also, i believe in both bash and zsh setting env variables before a command shouldn't use the $ prefix so i changed that as well. :)

[rachelnicole]

This is great! Thank you :D