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/markdown/injections.scm

@@ -1,17 +1,26 @@
 (fenced_code_block
   (info_string
     (language) @_lang)
-  (code_fence_content)
-    @content
-    (#set-lang-from-info-string! @_lang)
-    (#exclude_children! @content))
+  (code_fence_content) @injection.content
+  (#set-lang-from-info-string! @_lang))
 
-((html_block) @html @combined)
+((html_block) @injection.content 
+ (#set! injection.language "html")
+ (#set! injection.combined)
+ (#set! injection.include-children))
 
-((minus_metadata) @yaml (#offset! @yaml 1 0 -1 0))
-((plus_metadata) @toml (#offset! @toml 1 0 -1 0))
+((minus_metadata) @injection.content 
+ (#set! injection.language "yaml") 
+ (#offset! @injection.content 1 0 -1 0)
+ (#set! injection.include-children))
+
+((plus_metadata) @injection.content 
+ (#set! injection.language "toml") 
+ (#offset! @injection.content 1 0 -1 0)
+ (#set! injection.include-children))
 
 ([
   (inline)
   (pipe_table_cell)
- ] @markdown_inline (#exclude_children! @markdown_inline))
+ ] @injection.content
+ (#set! injection.language "markdown_inline"))