Add Dinesh Subhraveti to MAINTAINERS

Docker-DCO-1.1-Signed-off-by: Dinesh Subhraveti <dineshs@altiscale.com> (github: dineshs-altiscale)
Merge pull request #6060 from dineshs-altiscale/maintainers

Add Dinesh Subhraveti to MAINTAINERS
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