fix(demo): update GitHub stars link

[Panquesito7]

Summary

• Update GitHub stars link.

Type of change

• [ ] Bug fix (added a non-breaking change which fixes an issue)
• [x] New feature (added a non-breaking change which adds functionality)
• [ ] Updated documentation (updated the readme, templates, or other repo files)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)

How Has This Been Tested?

I don't think this applies here.

• [ ] Ran tests with composer test
• [ ] Added or updated test cases to test new features

[DenverCoder1]

On second look, it appears that the github-buttons code requires the link to be in that format for the number of stars to show up, so I think this should be reverted for now.