A missing backtick caused a formatting error in restore/README.md

Description

Add the missing backtick.

Motivation and Context

This is a trivial fix to a formatting issue in restore/README.md

How Has This Been Tested?

Visually checked the new formatting.

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)
• Documentation (add or update README or docs)

Checklist:

• 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.