Clarification about 'docker build --build-arg'
Clarification about 'docker build --build-arg'

See #22860

Signed-off-by: Nahum Shalman <9c78b6d62d7c8f15c2afb7bdd593942082aba2cc@omniti.com>

cpuguy83/cli,docker/cli,Zebrilee/cli,e11137/cli,riyazdf/cli,redpanda/cli,dnephin/cli,allencloud/cli,Zebrilee/cli,ashfall/cli,cpuguy83/cli,docker/cli,allencloud/cli,riyazdf/cli,ashfall/cli,thaJeztah/cli,e11137/cli,redpanda/cli,thaJeztah/cli,dnephin/cli