restore logo for README.md

Docker-DCO-1.1-Signed-off-by: Alex Hirsch <ax.warhawk@gmail.com> (github: W4RH4WK)
Allow --net=none & -h

Docker-DCO-1.1-Signed-off-by: Victor Vieux <vieux@docker.com> (github: vieux)
add tests

Docker-DCO-1.1-Signed-off-by: Victor Vieux <vieux@docker.com> (github: vieux)
Docs: Fixed logged-in header username label target
Docker-DCO-1.1-Signed-off-by: O.S. Tezer <ostezer@gmail.com> (github: ostezer)
Added highlight for the COPY instruction

Docker-DCO-1.1-Signed-off-by: Asbjorn Enge <asbjorn@hanafjedle.net> (github: asbjornenge)
Merge pull request #6361 from asbjornenge/tmlang_copy

Add contribute/syntax highlight for the COPY instruction
Merge pull request #6372 from ostezer/docs-fix-logged-in-hdr

Docs: Fixed logged-in header username label target
Merge pull request #6307 from W4RH4WK/master

restore logo for README.md
Merge pull request #6365 from vieux/allow_net_none_h

Allow --net=none and -h
Fix go vet errors

Docker-DCO-1.1-Signed-off-by: Alexandr Morozov <lk4d4math@gmail.com> (github: LK4D4)