There's not much end-user documentation the Tree-sitter project can really provide. It's a programming interface. The stuff that an Emacs, NeoVim, ... user is actually interacting with depends on the integration in the editor. So it's up to those docs to explain what features they expose based on Tree-sitter.

For example, the multiple cursor thing at the end is enabled by having the concrete syntax tree from Tree-sitter's parse, but Tree-sitter has nothing whatsoever to do with the cursors: it just provides locations in the text based on particular queries (like "all `identifier` nodes named 'foo' that are sub-nodes of this other node").

Even the headliner feature, syntax highlighting, isn't provided directly by Tree-sitter. It's up to the client system to inspect the syntax tree and apply attributes to its rendered text -- however it does that rendering.