doc: add link to post-installation setup wizard in README

[lemeurherve]

This PR adds a link to https://www.jenkins.io/doc/book/installing/docker/#setup-wizard as detailled steps for a quickstart demo in order to avoid doc duplication.

Closes:

• No detailed steps of quick-start demo in master branch  #969

Testing done

N/A

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• Ensure that the pull request title represents the desired changelog entry
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[MarkEWaite]

Thanks!. I've offered an alternate phrasing proposal and used a link that describes the destination of the link rather than the word "here". If we want to include the word "interface", then I think the phrasing should be

To access the Jenkins interface ...

[MarkEWaite]

Thanks!