Update GUIDE.md

[REWBrianH]

Increase indentation for correct display on github.com

Description

Motivation and Context

• I have raised an issue to propose this change (required)

How Has This Been Tested?

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:

• My code follows the code style of this project.
• I have tested this change and prove it works
• I've read the CONTRIBUTION guide
• I have signed-off my commits with git commit -s

[derek]

Thank you for your contribution. I've just checked and your commit doesn't appear to be signed-off. That's something we need before your Pull Request can be merged. Please see our contributing guide.
Tip: if you only have one commit so far then run: git commit --amend --signoff and then git push --force.