clarify that only one of binder and .binder can be used at once
MODIFY
docs/source/usage.rst
docs/source/usage.rst
@@ -72,14 +72,14 @@ specify the ``branch-name`` or ``commit-hash``. For example::
Where to put configuration files
================================
-``repo2docker`` will look for configuration files in either:
+``repo2docker`` will look for configuration files in:
* A folder named ``binder/`` in the root of the repository.
* A folder named ``.binder/`` in the root of the repository.
* The root directory of the repository.
-If either the folder ``binder/`` or ``.binder/`` is located at the top level of
-the repository, only configuration files in that folder will be considered.
+`repo2docker` searches for these folders in order (``binder/``, ``.binder/``,
+root). Only configuration files in the first identified folder are considered.
Check the complete list of :ref:`configuration files <config-files>` supported
by ``repo2docker`` to see how to configure the build process.

clarify that only one of binder and .binder can be used at once