tstest/integration/vms: consistently use two dashes for command-line switches
@@ -26,7 +26,7 @@ This test also requires the following:
- the user running these tests must have access to `/dev/kvm` (being in the
`kvm` group should suffice)
-The `-no-s3` flag is needed to disable downloads from S3, which require
+The `--no-s3` flag is needed to disable downloads from S3, which require
credentials. However keep in mind that some distributions do not use stable URLs
for each individual image artifact, so there may be spurious test failures as a
result.
