Improve wording about backwards compatibility

Author: uda

README.md

@@ -251,7 +251,7 @@ Extra property can be added to logging statement as follows:
 logger.info("test log statement", extra={'props': {'extra_property': 'extra_value'}, 'tags': ['app:name']})
 ```
 
-_For backwards compatibility, properties added in `props` take precedence over those set in the root of `extra`. This is relevant only for logs formatted by `JSONLogFormatter`, other formatters never printed the `props` details._
+_For backwards compatibility, properties added in `props` are extracted to the root and take precedence over those set directly in the root of `extra`. This is relevant only for logs formatted by `JSONLogFormatter`, other formatters never printed the `props` details._
 
 ### Forced overriding correlation-id
 A custom correlation id can be passed to logging statement as follow: