(#78) Update Git Release Manager missing token msg

[corbob]

Description Of Changes

Update message when Git Release Manager can't be used to include environment variables to check.

Motivation and Context

It's not immediately obvious what environment variables are used for this, so having it in the message allows the user to self-correct.

Testing

YOLO :shipit:

Change Types Made

• [ ] Bug fix (non-breaking change)
• [x] Feature / Enhancement (non-breaking change)
• [ ] Breaking change (fix or feature that could cause existing functionality to change)
• [ ] PowerShell code changes.

Related Issue

Fixes #78

Change Checklist

• [ ] Requires a change to the documentation
• [ ] Documentation has been updated
• [ ] Tests to cover my changes, have been added
• [ ] All new and existing tests passed.
• [ ] PowerShell v2 compatibility checked.

[gep13]

@corbob thanks for getting this fixed up!