Update contributing guide for new release notes system

Author: dstansby

docs/developers/contributing.rst

@@ -216,8 +216,8 @@ The documentation consists both of prose and API documentation. All user-facing
 and functions are included in the API documentation, under the ``docs/api`` folder
 using the `autodoc <https://www.sphinx-doc.org/en/master/usage/extensions/autodoc.html>`_
 extension to sphinx. Any new features or important usage information should be included in the
-user-guide (``docs/user-guide``). Any changes should also be included in the release
-notes (``docs/release-notes.rst``).
+user-guide (``docs/user-guide``). Any changes should also be included as a new file in the
+:file:`changes` directory.
 
 The documentation can be built locally by running::
 
@@ -350,7 +350,7 @@ appropriate suffix (e.g. `v0.0.0a1` or `v0.0.0rc2`).
 
 Set the description of the release to::
 
-    See release notes https://zarr.readthedocs.io/en/stable/release.html#release-0-0-0
+    See release notes https://zarr.readthedocs.io/en/stable/release-notes.html#release-0-0-0
 
 replacing the correct version numbers. For pre-release versions,
 the URL should omit the pre-release suffix, e.g. "a1" or "rc1".