Update cursorless reference, help terms and docs

[Will-Sommers]

What

Addresses notes in this issue https://github.com/cursorless-dev/cursorless-vscode/issues/451. After using it just for a few minutes on my branch, its been really help as it avoids collision with knausj "curse" commands.

Other thoughts:

• Ultimately would like to make some of the terms configurable but this has already helped me trigger the cheatsheet without as any error.
• Triggering "docs" in .talon looks like a cludge to me

Questions:

• No idea re: testing this? I tested it locally and it looks good.

Checklist

• [ ] I have added tests

[pokey]

I think this PR is still a win, esp if the docs immediately tell you how to use the cheatsheet for those who were expecting old "cursorless help" behaviour

[AndreasArvidsson]

I think we should probably add these commands to a csv file.

[pokey]

this one is waiting on #884