:memo: Updating README.md.

- Switching 'plugin' to 'package' in description.
- Adding 'plugin' to the SEO list.
- Adding 'Extension' to the list as well.
:memo: Updates README.md

- Adds instructions about how to bind 'f' to jumpy:toggle.
Updates CHANGELOG.md.
Prepare 1.4.1 release
:memo: Updates README.md.

- Pronoun not clear.
Adds scaffolding for toggle spec tests.

- Uses a markdown file so I can have folding.
New failing test for foldable regions.

- It should fail now before the fold and implementation.
- This makes sure it lines up though. I'll want dj to be the next label
  at B1.
Working fold in spec test now.

- Test is legit.
Fixing package description.