Allow user to add mu-plugins folder

[liamdefty]

Description

Allow user to specify mu-plugins folder to be mount. Fixes #27 27

Change Log

Added

• Allow user to specify mu-plugins folder to be mounted [#27]

Screenshots/Videos

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Types of changes (if applicable):

• [ ] Bug fix (non-breaking change which fixes an issue).
• [X] New feature (non-breaking change which adds functionality).
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected).

Checklist (if applicable):

• [X] Meets provided linting standards.