Home Assistant documentation is pretty thorough, but that brings its own problems - information can be quite hard to find, particularly for newcomers.
Using the search box typically brings up only three or four results, several of which will relate to integrations. For example, a search for “units of measurement” gives:
The same Google site search (“units of measurement site:www.home-assistant.io/docs/”) brings up nine references (only the first couple shown here) starting with the one that is probably most relevant:
I’m not suggesting that this should replace the existing search box, but it would be a useful addition.