https://en.wikipedia.org/wiki/URI_fragment
The text following the hash in a URL is called a fragment. Your browser will jump to whichever element in the page has an ID matching the fragment text. If you only link the fragment, then the browser will jump to the relevant part of the page you've currently loaded.
You can give almost any HTML tag an ID that can be skipped to using a URL fragment; <h3> is just the one I used in that instance. Here is another application from pokemondb's pokedex (try clicking the blue navbar at the top):
https://pokemondb.net/pokedex/bulbasaur#dex-moves
I don't advertise URL fragments in the formatting guide because I think people would overuse them. You can do what you think is reasonable though.
