Fix typo in event category filter box
There is a typo in the event category displayed in the event category filter: "TYPO3 Usergoup" --> "TYPO3 Usergroup" https://typo3.org/community/events/
There is a typo in the event category displayed in the event category filter: "TYPO3 Usergoup" --> "TYPO3 Usergroup" https://typo3.org/community/events/