docs/hacking.md: fix osupgrades link
@@ -295,7 +295,7 @@ OPENSHIFT_INSTALL_RELEASE_IMAGE_OVERRIDE=quay.io/user/origin-release:v{version n
## Hacking on `machine-os-content`
If you own part of the operating system (from kernel to kubelet) you
-are part of the `machine-os-content`. More information in [OSUpgrades.md].
+are part of the `machine-os-content`. More information in [OSUpgrades.md](docs/OSUpgrades.md).
You will want a workflow for testing changes to a cluster.
### Directly applying changes live to a node
