Keyboard shortcuts

[lklyne]

Add a page that documents keyboard shortcuts across Aerie UI.

• Link in sidebar at bottom below glossary for discoverability
• Separated into sections for different pages and panels
• Adds a <Shortcut /> component that wraps the <kbd> html element with a bit more padding

Future work:

• This list may not be exhaustive. We should continue the round up and add additional shortcuts as they come up
• Could also be useful to add docs around the context menus
• We may consider adding a link to this from within aerie-ui

[AaronPlave]

A few small comments but otherwise looks great!

[dandelany]

This looks great, thanks @lklyne! I'll go ahead and merge/publish this now since it's not directly related to the 2.13 release.