Update README.md

README.md

@@ -165,6 +165,10 @@ Provides tree-to-HTML serialization functionality.
 ####• Serializer.ctor([treeAdapter, options])
 Creates new reusable instance of the `Serializer`. Optional `treeAdapter` argument specifies input tree format. If `treeAdapter` argument is not specified, `default` tree adapter will be used.
 
+`options` object provides the serialization algorithm modifications (**Warning:** switching default options causes HTML5 specification violation. However, it may be useful in some cases, e.g. markup instrumentation. Use it on your own risk.)
+
+*  **options.encodeHtmlEntities** - HTML-encode characters like `<`, `>`, `&`, etc.  Default: `true`.
+
 
 *Example:*
 ```js