Fixed numerous inconsistencies in command help text

* Replaced docker with Docker.
* Consistently used STDIN, STDOUT, STDERR.
* Consistently used TTY.
* Fixed some grammar and spelling issues.
* Fixed references to the index.

Docker-DCO-1.1-Signed-off-by: James Turnbull <james@lovedthanlost.net> (github: jamtur01)

Docker-DCO-1.1-Signed-off-by: James Turnbull <james@lovedthanlost.net> (github: SvenDowideit)
Update cli.md and man pages to match current cli

Docker-DCO-1.1-Signed-off-by: SvenDowideit <SvenDowideit@home.org.au> (github: SvenDowideit)
Merge pull request #6790 from SvenDowideit/pr_out_update_cli_md

update cli.md