Use browser tests to screenshot the most important use cases

[Macroz]

We can use use browser tests to screenshot the most important use cases and add that as automatic documentation.

It would be nice to do even a small part of these ideas. This ticket can be split also.

• As a first step let's just make sure the screenshots from a whole pass of browser tests are valid and output the best and most descriptive ones to somewhere like /docs/screenshots folder.
• The names of the screenshots should be relevant (the current naming is ok for test debugging but we can make a new copy for each sensible image with a descriptive and relevant name. Sequence numbers could be useful to order the screenshots.
• Consider saving a separate Markdown file that links to the screenshots or use plain folder view of GitHub.
• Consider if we could have the screenshots from /manual be automated. Perhaps with some or no markings on the screenshots.