README: "Related": add panflute

Author: ickc

README.md

@@ -200,6 +200,7 @@ print(pypandoc.get_pandoc_formats())
 [Docverter](http://www.docverter.com/), which offers `pandoc` as a service (plus some extra goodies).
 * See [pyandoc](http://pypi.python.org/pypi/pyandoc/) for an alternative implementation of a `pandoc`
 wrapper from Kenneth Reitz. This one hasn't been active in a while though.
+* See [panflute](https://github.com/sergiocorreia/panflute) which provides `convert_text` similar to pypandoc's. Its focus is on writing and running pandoc filters though.
 
 ## Contributing