main-de-changes.md

 Adaptions of language file `/usr/share/jitsi-meet/lang/main-deFAIRMEETING2021.json` (original: `main-deDISTRO.json`)
 
+Can be applied on all brands (brand customizations happen in CSS and welcomePageAdditionalCard.html only). 
+
 ```
 section welcomepage (may be specific for branded domains):