Documentation, plus one piece of contextual help in the settings form. No code path changes, no configuration changes, no breaking changes: upgrading from 1.0.3 is safe.
Documentation and diagnostics. No behavior change in the endpoints, no configuration change, no breaking change: upgrading from 1.0.2 is safe.
Both changes come from the same exercise: installing the published 1.0.2 from drupal.org into a fresh Drupal 11 site and following the README as a newcomer would, rather than as its author.