explain this better

README.md

@@ -224,7 +224,7 @@ For more examples of customizing the sanitization process to include the tags yo
 
 `NodeFilters`s can operate either on HTML elements or text nodes using CSS selectors. Each `NodeFilter` must define a method named `selector` which provides an instance of `Selma::Selector`. If elements are being manipulated, `handle_element` must be defined, taking one argument, `element`; if text nodes are being manipulated, `handle_text_chunk` must be defined, taking one argument, `text_chunk`. `@config`, and `@result` are available to use, and any changes made to these ivars are passed on to the next filter.
 
-`NodeFilter` also has an optional method, `after_initialize`, which is run after the filter initializes. This can be useful in setting up a custom state for `result` to take advantage of.
+`NodeFilter` also has an optional method, `after_initialize`, which is run after the filter initializes. This can be useful in setting up a fresh custom state for `result` to start from each time the pipeline is called.
 
 Here's an example `NodeFilter` that adds a base url to images that are root relative: