Disable automatic document highlighting in eglot

This causes lagging while highlighting symbols, and the highlighting itself does
not add much value.  Disabling it thus does not hurt and gets rid of the
lagging.

init.el

@@ -1478,7 +1478,10 @@
 
 (use-package eglot
   :ensure t
-  :commands (eglot-ensure))
+  :commands (eglot-ensure)
+  ;; Highlighting takes a lot of time and does not add much value, so let's just
+  ;; disable it
+  :init (setq eglot-ignored-server-capabilites '(:documentHighlightProvider)))
 
 
 ;; * Mail