change wording

src/main/resources/i18n/strings.properties

@@ -541,7 +541,7 @@ recoveryKey.alreadyExists.description=Your vault "%s" is already present in your
 
 recoveryKey.noDDirDetected.title=Invalid Selection
 recoveryKey.noDDirDetected.message=Your selection is not a vault
-recoveryKey.noDDirDetected.description=The selected folder must contain a subfolder named "d".
+recoveryKey.noDDirDetected.description=The selected folder must be a valid Cryptomator vault.
 
 recoveryKey.recoverVaultConfig.title=Recover Vault Config
 recoveryKey.recoverMasterkey.title=Recover Masterkey