chore(injections)!: update injection syntax to 0.9

Since 0.9, @lang syntax is still available as fallback but will soon be deprecated.
Because of that, new syntax should be adopted once 0.9 becomes the
baseline requirements for nvim-treesitter

- update health check
- update doc

queries/lua/highlights.scm

@@ -243,5 +243,7 @@
 
 (string) @string
 
+(escape_sequence) @string.escape
+
 ;; Error
 (ERROR) @error