Improve typo3.org help page (https://typo3.org/help)

Improve typo3.org help page (https://typo3.org/help)

I think it would be useful if the help page https://typo3.org/help also mention

• usergroups https://typo3.org/community/meet/user-groups and official TYPO3 GMBH services (SLA and project reviews).