Add link to triage documentation

It took me a while to find the [triage documentation](https://github.com/web-platform-tests/wpt.fyi/blob/main/docs/triaging.md). Can we add a link to make this more discoverable? Perhaps an ℹ️ icon near the toggle, or even just a link to https://github.com/web-platform-tests/wpt.fyi/tree/main/docs from the [about page](https://wpt.fyi/about)?