The documentation should prompt users to install `util-linux-extra` to use `newgrp docker`

[linghengqian]

Tell us about your request
A clear and concise description of what you want to happen or the change you would like to see

• The documentation should prompt users to install util-linux-extra to use newgrp docker. See https://docs.docker.com/engine/install/linux-postinstall/ .

• 

• After all, Ubuntu 26.04 doesn't have newgrp installed by default.

lingh@DESKTOP-T569R06:~$ newgrp docker
Command 'newgrp' not found, but can be installed with:
sudo apt install util-linux-extra
lingh@DESKTOP-T569R06:~$

Which service(s) is this request for?
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• Docker Engine

Tell us about the problem you're trying to solve. What are you trying to do, and why is it hard?
A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]

• Updating documents is not difficult at all.

Are you currently working around the issue?
A clear and concise description of any alternative solutions or features you've considered or are using today.

• No.

Additional context
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• Null.