Readme function name issue: characteristic_enable_notification_succeeded / characteristic_enable_notification_failed

[tastymushroom]

In the Readme.md the callbacks for enable notifications are incorrect and therefore looks like the code doesn't work when implemented.

Readme.md has: characteristic_enable_notification_failed
correct function name: characteristic_enable_notifications_failed

Readme.md has: characteristic_enable_notification_succeeded
correct function name: characteristic_enable_notifications_succeeded

This is a obviously confusing as there is no example for notifications and I thought the callback code wasn't working!