Docker engine activate - help has outdate information

[Vireche]

Description
Docker engine activate references docker.com to get information about licenses. This should be directed to mirantis.com.

This command is being removed in version 20, this change would only be for 19.03 to avoid user confusion

Steps to reproduce the issue:
docker engine activate --help

Describe the results you received:

Usage:  docker engine activate [OPTIONS]

Activate Enterprise Edition.

With this command you may apply an existing Docker enterprise license, or
interactively download one from Docker. In the interactive exchange, you can
sign up for a new trial, or download an existing license. If you are
currently running a Community Edition engine, the daemon will be updated to
the Enterprise Edition Docker engine with additional capabilities and long
term support.

For more information about different Docker Enterprise license types visit
https://www.docker.com/licenses

For non-interactive scriptable deployments, download your license from
https://hub.docker.com/ then specify the file with the '--license' flag.

Output of docker version:

Client: Docker Engine - Community
 Cloud integration: 1.0.1
 Version:           19.03.13
 API version:       1.40
 Go version:        go1.13.15
 Git commit:        4484c46d9d
 Built:             Wed Sep 16 17:02:36 2020
 OS/Arch:           linux/amd64
 Experimental:      true

[thaJeztah]

This was part of the docker engine subcommands, which have been removed;

• Remove "docker engine" subcommands #2207
• [epic] Remove "engine activate/check/update" subcommands #2213