bug#60983: 29.0.60; Tree-sitter user-level control

[Yuan Fu]

I just read the new manual sections, thanks for the work! Do we want to mention 
treesit-font-lock-recompute-features in the user manual? That’s the only way 
for someone to add/remove specific features (as opposed to changing the 
decoration level). (We might also want to mention that changing 
treesit-font-lock-features directly doesn’t have any effect, similar to 
treesit-font-lock-level.)

treesit-font-lock-recompute-features is intended to be used in major mode 
hooks, like

(add-hook 'c-ts-mode-hook #'c-ts-setup)

(defun c-ts-mode-setup ()
  (treesit-font-lock-recompute-features
   '(emacs-devel)
   '(property bracket delimiter operator variable function)))

Yuan