Update fish shell completions.

Fixes #9550

Signed-off-by: Barnaby Gray <barnaby@pickle.me.uk>
Merge pull request #9551 from barnybug/9550-fish-completions

Update fish shell completions.
Add master builds url to readme.

Docker-DCO-1.1-Signed-off-by: Jessica Frazelle <jess@docker.com> (github: jfrazelle)
Merge pull request #9639 from jfrazelle/advertise-master-builds

Add master builds url to readme.
Set HTTP upgrade headers when hijacking the connection

Signed-off-by: Jean-Tiare Le Bigot <admin@jtlebi.fr>