Change 'Uploading context' wording

Docker-DCO-1.1-Signed-off-by: Ryan Stelly <ryan.stelly@live.com> (github: FLGMwt)
implement wait on freeze

Docker-DCO-1.1-Signed-off-by: Victor Vieux <vieux@docker.com> (github: vieux)
Merge pull request #6082 from FLGMwt/2342-change-wording-uploading-context

Change 'Uploading context' wording
Update builder.md
Merge pull request #6191 from snowch/patch-1

Small clarification
Merge pull request #6187 from vieux/wait_freeze

Implement wait on freeze