[keycloak-user] Needs review: Proposed fixes to the german translations of login pages in Keycloak base theme

Hello group, I reworded some translations and fixed some spelling errors in the german translations of the login pages in the base theme: https://github.com/keycloak/keycloak/pull/2825 Would be great if some other native german speakers would take a quick look. Thanks in advance! Cheers, Thomas