Update CONTRIBUTING.md

CONTRIBUTING.md

@@ -53,27 +53,13 @@ git switch -c <your-branch-name>
 
 With this branch checked-out, make the desired changes to the package.
 
-### Updating the Vega-Lite version
-
-If your desired changes include updating the Vega-Lite that Altair uses
-you need to change the following section in ``tools/generate_schema_wrapper.py``
-to the desired version number
-
-```python
-SCHEMA_VERSION = {
-    "vega-lite": {"v5": "v5.15.0"},
-}
-```
-
-Then regenerate any automatically generated files
-as described in the next section.
-
-### Updating any automatically generated files
-
 A large part of Altair's code base is automatically generated.
 After you have made your manual changes,
 make sure to run the following to see if there are any changes
-to the automatically generated files: ``tools/generate_schema_wrapper.py``.
+to the automatically generated files: `python tools/generate_schema_wrapper.py`.
+
+For information on how to update the Vega-Lite version that Altair uses,
+please read [the maintainers' notes](NOTES_FOR_MAINTAINERS.md).
 
 ### Testing your Changes