docs: update RUNC.md
containerd is built with OCI support and with support for advanced features provided by [runc](https://github.com/opencontainers/runc).
-We depend on a specific `runc` version when dealing with advanced features. You should have a specific runc build for development. The current supported runc commit is described in [`vendor.conf`](vendor.conf). Please refer to the line that starts with `github.com/opencontainers/runc`.
+We depend on a specific `runc` version when dealing with advanced features. You should have a specific runc build for development. The current supported runc commit is described in [`go.mod`](go.mod). Please refer to the line that starts with `github.com/opencontainers/runc`.
For more information on how to clone and build runc see the runc Building [documentation](https://github.com/opencontainers/runc#building).
