Update maintainer reference to Executable Books team

Author: mmcky

setup.py

@@ -15,7 +15,7 @@
 - Complete internationalization support for 33 languages
 - Customizable styling with multiple theme options
 
-This project is maintained and supported by [najuzilu](https://github.com/najuzilu).
+This project is maintained and supported by the [Executable Books team](https://github.com/executablebooks/).
 """
 
 SHORT_DESCRIPTION = "A Sphinx extension for producing proofs, theorems, axioms, etc."