fix typo in upgrade troubleshooting guide

docs/upgrading.rst

@@ -40,8 +40,8 @@ like:
    Error from server (NotFound): secrets "oas-wekan-variables" not found
 
 This is not a problem, but it *does* mean you need to add an oauth secret for
-Wekan to the file ``secrets-backup/oas-oauth-variables.yaml``. Copy the
-wordpress line, rename the field to ``wordpress_oauth_client_secret`` and enter
+Wekan to the file ``secrets-backup/oas-oauth-variables.yaml``. Copy one of the
+lines under "data:", rename the field to ``wekan_oauth_client_secret`` and enter
 a different random password. Make sure to base64 encode it (``echo "<your random
 password>" | base64``).