Update README.md

Author: fhlavac

README.md

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 This repo contains React Data view implementation.
 
+### Branches
+`main` - PatternFly 6 implementation
+
+`v5` - PatternFly 5 implementation
+
+> NOTE: If new features are not needed in `v5,` they should be added directly to the `main` branch. For bug fixes, it is preferred to fix the bug for both versions (fix in one branch and cherry-pick to another). Pulling new changes from 5 to 6 and vice versa is not recommended using `rebase`. Rather, always cherry-pick specific commits.
+
 ---
 ## Contribution guide