Document CommentDelimiters configuration option

content/en/docs/topics/config/index.md

@@ -207,6 +207,42 @@ BlockIgnores = (?s) *({< output >}.*?{< ?/ ?output >}), \
 (?s) *({< highlight .* >}.*?{< ?/ ?highlight >})
 ```
 
+#### CommentDelimiters
+
+`CommentDelimiters` allow you to override standard, HTML comment delimiters (`<!-- -->`).
+
+Custom comment delimiters are useful when using non-standard markup which do not allow HTML-style comments.
+
+```ini
+[formats]
+mdx = md
+
+[*.mdx]
+BasedOnStyles = Vale
+
+CommentDelimiters = {/*, */}
+```
+
+When `CommentDelimiters` are set, you can take full advantage of [markup-based configuration](/docs/topics/scoping/#markup-based-configuration) to enable or disable specific rules within a section.
+
+For instance, when using MDX:
+
+```markup
+{/* vale off */}
+
+This is some text ACT test
+
+This is some text ACT test
+
+{/* vale on */}
+
+{/* vale vale.Redundancy = NO */}
+
+This is some text ACT test
+
+{/* vale vale.Redundancy = YES */}
+```
+
 #### TokenIgnores
 
 {{< alert icon="👉" context="info">}}