MAINT: Explain jupytext dependency (#1353)

setup.cfg

@@ -39,6 +39,7 @@ install_requires =
     docutils>=0.15,<0.17
     jsonschema
     jupyterbook-latex~=0.3.1
+    # Include Jupytext to ensure users have the right version, even if not strictly necessary
     jupytext>=1.8,<1.11
     linkify-it-py~=1.0.1
     myst-nb~=0.12.0