use "latest" in path to github icon #3388

[pdurbin]

RFI Checklist

1. Related Issues

• Documentation: Guides have broken github icons in the footer. #3388 Documentation: Guides have broken github icons in the footer.

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2. Pull Request Checklist

• Functionality completed as described in FRD
• Dependencies, risks, assumptions in FRD addressed
• Unit tests completed
• Deployment requirements identified (e.g., SQL scripts, indexing)
• Documentation completed
• All code checkins completed

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3. Review Checklist

After the pull request has been submitted, fill out this section.

• Code review completed or waived
• Testing requirements completed
• Usability testing completed or waived
• Support testing completed or waived
• Merged with develop branch and resolved conflicts

This work connects to #3388.

[coveralls]

Coverage remained the same at 8.583% when pulling 74d6846 on 3388-github-icon into 9f93e7b on develop.