f-m-p misleading log warning if oc binary is missing

If f-m-p like fabric8:resource-apply or fabric8:deploy goals are executed on env without oc binary on $PATH installed. There's a warning stating to run fabric8:install goal that isn't shipped in productized version of f-m-p.

In Getting started guide we already assume that users are aware of oc binary, because they're required to run oc login first, before executing any Maven goal. However, we should probably fix the warning message not to mention unsupported goal.

F8: Could not find commands oc or kubectl. Please try running `mvn fabric8:install` to install the necessary binaries and ensure they get added to your $PATH