docs: add notes about root requirements for commands

[JTorreG]

Adds notes to make readers aware of which commands need to be run as root, in two ways:

• In docs where there are 1 or 2 root commands, it adds a note in the step before the command
• In docs with many root commands, it adds a note callout in the introductory section of the page

Closes #171

[github-actions]

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[ac000]

Adds notes to make readers aware of which commands need to be run as root, in two ways:

* In docs where there are 1 or 2 root commands, it adds a note in the step before the command

Is that really necessary? as that's precisely what the # signifies... (which is a well known idiom)