Add guidelines on how to use components together

The repo README does not clearly state the purpose of the extension or how the components can be used together. Similarly, we lack any sort of overview on the main PF website that shows how these components can be put together.

We should update/add these and make it clearer how these components can be used together and what they are for.

From Andrew Ballantyne:

I’m not sure what I am supposed to be able to glean from the docs on patternfly.org. The Repo README seems a bit lacking too… If I wanted to use this, how do I see what it is offering? Do we have a rendering/sandbox mode of it somewhere?

I guess I was looking for the “how it all works together” experience, and I can’t find one that shows me that. We were having a UX meeting and I was curious what the experience was like to have a catalog, and felt like this set of data very weirdly structured. I guess if I was familiar with the extension, these individual components would be helpful as any component documentation in PF docs are — looking at use-cases and props and what have you — but it seemed to be missing the “bigger picture” stuff. I guess an overview page/README would solve that in some degree

Jira Issue: PF-2492

Start by reviewing the repository README and the existing content on patternfly.org to identify the current explanation of the extension and its components. Done means both surfaces explain the extension’s purpose, show how components work together, and provide the requested broader overview.