Ensure demo (and defaults) support tab navigation #174
Description
Looking at this page:
https://prosemirror.net/examples/basic/
I can tab over the menu. I can tab and edit the content in the WYSIWYG, but I can't get to the menu without a mouse.
This should be fixed in the demo. It should also be a default for setting up ProseMirror. Most folks won't bother to set up accessibility features.
I see this was reported a few years ago too:
https://discuss.prosemirror.net/t/enabling-accessibility-on-prosemirror/3147