Caching Improvement

[kzadrozny]

Add enhancement that allows fragment caching to be cleared when a page is edited and saved.

Possible code to use:

def save(self, *args, **kwargs):
        """Create a template fragment key.
        Then delete the key."""
        key = make_template_fragment_key(
            " <--  name of our template fragment --> ",
            [self.id] 
        )
        cache.delete(key)
        return super().save(*args, **kwargs)
``