Is your feature request related to a problem? Please describe.
Recently while using the editor I've been thinking about the new Edit and Navigation mode (#16500), and what it's like for users using the editor for the first time.

What does it mean when my block is highlighted with a blue border? My feeling is that it's ok if you're a mouse user, clicking on the block allows you to edit it.

If you're someone who primarily uses only the keyboard (as I quite often do), then I'm concerned that it might not be clear why nothing happens when attempting to type in a block in nav mode.

Describe the solution you'd like
One way to remedy this could be using tips. I think first and foremost, if a user finds themselves in navigation mode, it'd be great to show some kind of tip that tells them how to get back into edit mode.

Here's a little example of what this could look like to get the ball rolling:

If this seems too noisy, one option could be that the tip only appears if the user tries typing.

Describe alternatives you've considered
Perhaps typing should switch back into edit mode? This would rule out my other idea - #17185