Ref manual: Fix broken link

Author: jrobinAV

taipy/core/notification/registration_id.py

@@ -12,5 +12,5 @@
 from typing import NewType
 
 RegistrationId = NewType("RegistrationId", str)
-"""Registration identifier. It can be used to instantiate a `CoreEventConsumerBase^`."""
-RegistrationId.__doc__ = """Registration identifier. It can be used to instantiate a `CoreEventConsumerBase^`."""
+"""Registration identifier. It can be used to instantiate a `CoreEventConsumerBase`."""
+RegistrationId.__doc__ = """Registration identifier. It can be used to instantiate a `CoreEventConsumerBase`."""