Add a test criterion for documentation or getting started

When conducting the reading systems evaluations, some functions are possible but obscure or difficult to discover. This test could evaluate whether there is any information to help people get going with the reading system (with AT or other a11y related features).

Review the existing reading-system evaluation criteria and the current accessibility or getting-started guidance. Define a criterion that checks whether users can discover help for starting the reading system, including assistive-technology-related features; done means the criterion is specific enough to apply consistently.

Written by the indexing model from the issue text.