update singularity image

content/guides/running_applications/using_singularity.md

@@ -190,6 +190,11 @@ unset REGISTRY
 singularity exec docker://myaccount/myimage mycommand
 {{< /highlight >}}
 
+{{% notice info %}}
+If you get the error `FATAL: kernel too old` when using your Singularity image on the HCC clusters, that means the *glibc* version in your image is too new for the kernel on the cluster. One way to solve this is to use lower version of your base image (for example, if you have used Ubuntu:18.04 please use Ubuntu:16.04 instead).
+{{% /notice %}}
+
+
 All the Dockerfiles of the images we host on HCC are
 [publicly available here](https://github.com/unlhcc/singularity-dockerfiles)
 You can use them as an example when creating your own image. The only thing you need to note