Rename Apple Business Manager (ABM) to Apple Business (AB) in articles/docs/handbook

[melpike]

Goal

User story
As an IT admin,
I want to see consistent terminology (Apple Business vs Apple Business Manager) in Fleet's articles/docs/handbook
so that I am not confused when referencing Apple products/documentation.

For help creating a user story, see "Writing a good user story" in the website handbook.

Change

• Rename Apple Business Manager in articles #42579

[melpike]

Note: keeping this in draft until the Apple Business release from Apple on April 14th.