[Docs] Add "Managing Recommendations" Guide

[YozoraXCII]

Description

Adds a guide for managing the Recommended collections in Plex using the visible_* attributes

Type of Change

Please delete options that are not relevant.

• [] Bug fix (non-breaking change which fixes an issue)
• [] New feature (non-breaking change which adds functionality)
• [] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation change (non-code changes affecting only the wiki)
• [] Infrastructure change (changes related to the github repo, build process, or the like)

Checklist

Please delete options that are not relevant.

• Updated Documentation to reflect changes
• [] Updated the CHANGELOG with the changes