docs: remove outdated docs, update "devstack guide"

Braden MacDonaldrequested to merge
update-docs into master

Removes a ton of outdated documentation. The only new doc is Devstack Guide (Tutor) which adds a helpful "cheatsheet" of Tutor commands.

Jira: https://tasks.opencraft.com/browse/MNG-4748

Edited by Braden MacDonald

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