Update Treeview/Highlights debugging instructions (#56)

Starting with nvim 0.9, the TSPlayground tree and highlight debugging are parts of neovim proper

README.md

@@ -63,6 +63,9 @@ tree-sitter, and should be usable by helix. To generate queries for NeoVim,
 run `./build-flavored-queries.py` (this is run as part of `npm run gen`).
 
 
+You can use the [`:InspectTree`](https://neovim.io/doc/user/treesitter.html#%3AInspectTree)
+command to explore the resulting parse tree, and [`:Inspect`](https://neovim.io/doc/user/lua.html#%3AInspect) to view highlight groups.
+
 ## Quirks of Just
 
 Just currently doesn't seem to support comments between attributes or within if