hooks: Remove backticks from CRI-O
hooks: Remove backticks from CRI-O

These backticks landed with the rest of the hook docs in 139d0841 (Add
support for oci-hooks to libkpod, 2017-08-12, #562).  But "CRI-O" is
the project name, so it doesn't need backticks.  We would need
backticks if we used the executable filename "crio".

Signed-off-by: W. Trevor King <f75897670c17327c42ab201733fb8a81ff9f4c34@tremily.us>

nalind/cri-o,vbatts/cri-o,rhatdan/cri-o,jwhonce/ocid,jwhonce/ocid,mikebrow/cri-o,kubernetes-incubator/cri-o,mikebrow/cri-o,kubernetes-incubator/ocid,kubernetes-incubator/ocid,jwhonce/ocid,vbatts/cri-o,kubernetes-incubator/cri-o,kubernetes-incubator/cri-o,rhatdan/cri-o,kubernetes-incubator/cri-o,rhatdan/cri-o,kubernetes-incubator/ocid,mikebrow/cri-o,vbatts/cri-o,mikebrow/cri-o,nalind/cri-o,vbatts/cri-o,nalind/cri-o,rhatdan/cri-o