be GDPR / DSGVO compliant

[noerw]

• [ ] extensive privacy hints at signup form (purpose, duration of storage, diesdas)
• [ ] automatically delete/anonymize PII when not needed anymore
• [ ] option to retrieve / request deletion of PII (hint to send mail to admin should be enough)
• [ ] clear statement of who has access rights to the raw data (e.g. List of Admins, LDAP ErstiWEOrga Group?)

see also https://datenschutz.saarland.de/themen/vereine/datenschutz-im-verein/