clarify documenation of includes

Author: jensens

README.md

@@ -57,8 +57,9 @@ Default: `constraints-mxdev.txt`
 
 Include one or more other INI files.
 
-The included file is read before main file, so the main file overrides included settings, if they appear in both sections.
-The included file is read depth first, so if the included file includes another file, this is read before the main file
+The included file is read before the main file, so the main file overrides included settings.
+Included files may include other files.
+Innermost inclusions are read first.
 
 If an included file is an HTTP-URL, it is loaded from there.