Cross-reference ModuleNotFoundError properly

Co-authored-by: Sviatoslav Sydorenko (Святослав Сидоренко) <[email protected]>

Author: smheidrich

source/guides/handling-missing-extras-at-runtime.rst

@@ -6,7 +6,7 @@ Handling missing optional dependencies ("extras") at runtime
 
 If your package has :ref:`optional dependencies ("extras")
 <metadata_provides_extra>` which the package consumer hasn't installed, the
-default outcome is an ordinary ``ModuleNotFoundError`` exception being raised
+default outcome is an ordinary :exc:`ModuleNotFoundError` exception being raised
 at the first attempted import of a missing module.
 
 This can make for a bad user experience, because there is no guidance about why