Shepherd Documentation

[TreesClouds]

Lots of Shepherd's current documentation within GitHub is currently difficult to read or completely out of date (like the sensors docs). A new and more comprehensive rewrite is needed to better onboard new members to the project. The medium (GitHub, Notion, Just the Docs, etc.) is yet to be decided. Additionally, information about Shepherd is spread in several places including the onboarding repo, so this information needs to be streamlined.

[WenQi7721]

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