The main help button in the plugin window shows the following text "For more information, visit https://revealer.cc/." But that link sends you to a webpage that a) has an expired SSL cert and b) is just a splash page that says it's shutting down. I'm including a screenshot of the current page in case the whole site disappears.

There are other links in the plugin that point to deeper URLs, and those appear to still have content.
Suggestions:
If it's OK to copy the docs I'll open a PR over there.