Add compatibility notes for #9

README.rst

@@ -76,6 +76,25 @@ Largely, that's it. There is a whole slew of utility code that you may
 or may not find useful, too. Look at the `full documentation
 <https://jfinkhaeuser.github.io/prance/#api-modules>`__ for details.
 
+
+Compatibility
+-------------
+
+As of version 0.8, we're using `flex <https://github.com/pipermerriam/flex>` as the default validation backend.
+The previous `swagger-spec-validator <https://github.com/Yelp/swagger_spec_validator>` still works, if you
+installed with the `ssv` dependencies.
+
+You can select the backend in the constructor of the parser(s):
+
+.. code:: python
+
+    parser = ResolvingParser('http://petstore.swagger.io/v2/swagger.json', backend = 'swagger-spec-validator')
+
+Note that the `flex` validator simply accepts integer status codes, despite them not being valid JSON.
+See `issue #5 <https://github.com/jfinkhaeuser/prance/issues/5>` for details. Therefore, `flex` also
+does not support the `strict` option.
+
+
 Contributing
 ============