Plugin docs aggregation

**Why are you updating / adding this documentation?**
We should have a way to aggregate the docs for plugins in github.com/bitops-plugins.

Each plugin would host a `docs/` directory of markdown files.
The bitops repo's docs build process would then clone each plugin repo, extract the docs, and include them in the build for the main docs page.

Start by inspecting the existing docs build process and the plugin repositories in github.com/bitops-plugins, including their docs/ directories. Determine how plugin repositories would be cloned and their Markdown files extracted. Done means the aggregated plugin documentation is included in the main docs build and appears on the main documentation page.

Written by the indexing model from the issue text.