Docs: Third Party Widgets

### Description

Given the availability of the first third-party widget for Dashboard 2.0 (thanks @sumitshinde-84!) - I want to see what we can do in the core documentation to support this, and advertise their existence.

I'm thinking a "Third Party Nodes" section in the Dashboard 2.0 documentation, where third-parties can list their nodes, and host their online documentation? Updates would need to be done via PRs to Dashboard 2.0 though, which is a tad annoying, but not sure there is a cleaner way?

Other option would be that we, within `ui-example` repo (https://github.com/FlowFuse/node-red-dashboard-2-ui-example) we include vitepress documentation example (what we use for Dashboard 2.0, entirely Markdown driven, with the ability to include Vue code too), such that, when forked, it auto deploys to github pages or something like that? That way, it's completely isolated to each node? We can then still have a "Third Party Nodes" section in the core documentation, that advertises and links off to each site?

### Have you provided an initial effort estimate for this issue?

I have provided an initial effort estimate