Hidden panel on storybook

[Pooya-Oladazimi]

Sometimes the panel gets hidden in the storybook (if one closes it accidentally). Users can restore it by pressing "d" on the keyboard.
Tested on Firefox.

Might be better to document it somewhere on the page as a hint for users. (like: in case you are not able to see the panel, press d)

[VincentKneip]

There's also a button on the top right corner to show the panel. But it's rather inconspicuous.