Update docs

Author: jacksleight

docs/helpers.md

@@ -27,7 +27,7 @@ Creates a new text node object.
 
 #### `Data::html($html|$tag, $attrs = [], $content = [], $marks = [])`
 
-Creates a new HTML node object.
+Creates a new HTML node object. Input is treated as raw HTML, so any text should be escaped with the `e()` helper.
 
 #### `Data::apply($item, ...$properties)`