add packaging guide for aio app pack

[shazron]

Packaging guide for the aio app pack command.
In the root of the Guides TOC.

How Has This Been Tested?

• yarn install && yarn build && yarn serve
• observe the contents of the /guides/packaging link and test any links

Screenshots (if appropriate):

Types of changes

• 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 change)

Checklist:

• I have signed the Adobe Open Source CLA.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.