Add notes to README.md about needing ostree-dev
Add notes to README.md about needing ostree-dev

Add notes to README.md about needing to install ostree-devel, or
libostree-dev, or building ostree from source.

Signed-off-by: Nalin Dahyabhai <f562fcb2a0b898bf0be1afc867ea92325d8f825f@redhat.com>

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