The detail page for plug-ins now includes the README from GitHub if there is one. For example, here’s the plug-in page for the Conversation on Micro.blog plug-in.
Most Markdown and basic HTML is supported, with one exception: images referenced in the README need to use full “https://” URLs, not relative paths in the GitHub repository.
Micro.blog checks for new versions of plug-ins every couple of hours. If the version has been updated, it will also update its copy of the README text.