contrib/cni: Fix README link
contrib/cni: Fix README link

The CNI plugins are now living in a repo of their own.

Signed-off-by: Samuel Ortiz <0ba86cb3f08bbb861958e54bd3438887adb4263c@linux.intel.com>

nalind/cri-o,mheon/cri-o,rhatdan/cri-o,rhatdan/cri-o,umohnani8/cri-o,apilloud/cri-o,14rcole/cri-o,jwhonce/ocid,14rcole/cri-o,mheon/cri-o,vbatts/cri-o,kubernetes-incubator/cri-o,mikebrow/cri-o,apilloud/cri-o,mikebrow/cri-o,14rcole/cri-o,apilloud/cri-o,mikebrow/cri-o,vbatts/cri-o,rhatdan/cri-o,jwhonce/ocid,14rcole/cri-o,kubernetes-incubator/ocid,kubernetes-incubator/ocid,kubernetes-incubator/cri-o,umohnani8/cri-o,kubernetes-incubator/cri-o,nalind/cri-o,vbatts/cri-o,mheon/cri-o,umohnani8/cri-o,jwhonce/ocid,umohnani8/cri-o,kubernetes-incubator/cri-o,vbatts/cri-o,rhatdan/cri-o,mheon/cri-o,kubernetes-incubator/ocid,mikebrow/cri-o,nalind/cri-o