Try:
for i in env resources volumes probe deployment-hook image build-secret triggers build-hook route-backends
do
  echo "oc set $i -h"
  oc set $i -h | grep -o "Use \"oc set $i options\" for a list of global"
done

Will see: all sub-commands (including 'triggers') of oc set give wrong info:

oc set env -h
Use "oc set env options" for a list of global
oc set resources -h
Use "oc set resources options" for a list of global
oc set volumes -h
Use "oc set volumes options" for a list of global
oc set probe -h
Use "oc set probe options" for a list of global
oc set deployment-hook -h
Use "oc set deployment-hook options" for a list of global
oc set image -h
Use "oc set image options" for a list of global
oc set build-secret -h
Use "oc set build-secret options" for a list of global
oc set triggers -h
Use "oc set triggers options" for a list of global
oc set build-hook -h
Use "oc set build-hook options" for a list of global
oc set route-backends -h
Use "oc set route-backends options" for a list of global

Shoud be: Use "oc options" for a list of global ...

Version-Release number of selected component (if applicable):
oc v1.4.0-alpha.0+f69b28e-909

Fixed in https://github.com/openshift/origin/pull/11703

With oc/openshift v1.4.0-alpha.0+90d8c62-1000, checked all `oc set sub-commands -h` and `openshift cli set -h`, the former shows 'Use "oc options" for a list of global ...', the latter shows 'Use "openshift cli options" for a list of global ...'