Add link to singularity fakeroot documentation

workflows/pytorch_GAN_zoo/README.md

@@ -15,7 +15,8 @@ To build the singularity container use the build script in this directory.
 ./build.sh
 ```
 
-This script will try to use singularities fakeroot support if you run as a
+This script will try to use singularities [fakeroot
+support](https://sylabs.io/guides/3.5/user-guide/fakeroot.html) if you run as a
 non-root user. If this is not supported on your system you can run the script as
 root.