Add documentation link to readme and project metadata

README.md

@@ -9,6 +9,10 @@ This project was initially a part of [lxml](https://github.com/lxml/lxml). Becau
 You can install this project directly via `pip install lxml_html_clean` or soon as an extra of lxml
 via `pip install lxml[html_clean]`. Both ways installs this project together with lxml itself.
 
+## Documentation
+
+[https://lxml-html-clean.readthedocs.io/](https://lxml-html-clean.readthedocs.io/)
+
 ## License
 
 BSD-3-Clause

setup.cfg

@@ -5,6 +5,8 @@ description = HTML cleaner from lxml project
 long_description = file:README.md
 long_description_content_type = text/markdown
 url = https://github.com/fedora-python/lxml_html_clean/
+project_urls =
+    Documentation = https://lxml-html-clean.readthedocs.io/
 author = Lumír Balhar
 author_email = [email protected]
 license = BSD-3-Clause