Add ABS migration guide

[PatAltimore]

Purpose

• Add ABS migration guide. Article is being relocated from docs.microsoft.com.

Does this introduce a breaking change?

[ ] Yes
[x ] No

Pull Request Type

What kind of change does this Pull Request introduce?

[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ x] Documentation content changes
[ ] Other... Please describe:

How to Test

N/A

What to Check

Verify that the following are valid

• N/A. Markdown is from docs.microsoft.com

Other Information