Add Linux Users Info about documentation HOT 4 CLOSED

I wrote content in d050b69 - could do with details checking over. @asb could you take a look?

from documentation.

Hi Ben, there are a number of issues I spotted. I think we need to be careful to make sure all commands are checked, even if they seem obvious - several of the examples listed don't work as described.

On Debian systems, adduser is prefered to useradd (it is a perl wrapper around the lower level useradd command). useradd doesn't prompt for a password for me, and doesn't create a home dir. Looking at it, I think it becomes correct as described when using adduser rather than useradd.

The sudoers section would be better if it explained that you're allowing them to sudo with no password. Just like adduser is preferred to useradd, deluser is preferred to userdel. visudo doesn't prompt me for a default editor. I'd make the changes myself, but I don't have time at the minute to properly verify all the commands.

from documentation.

Ok I'll check through it all tomorrow with a Pi. Yes - I think I meant adduser over useradd.

from documentation.

Maybe the bit about changing your password could link back to https://github.com/raspberrypi/documentation/blob/master/configuration/raspi-config.md#change-user-password ?

And maybe the bit about sudoers should link to https://github.com/raspberrypi/documentation/blob/master/linux/usage/root.md ?
(in fact, maybe it'd be a good idea to explain the implications of what "having sudo permissions" means i.e. any user with sudo rights has the ability to screw up the whole system)

from documentation.