docs: Add alt text

[ianlewis]

Description:

Adds alt text to the image in the README for accessibility purposes.

Related Issues:

N/A

Checklist:

• Review the CONTRIBUTING.md documentation.
• Add a reference to a related issue in the repository.
• Add a description of the changes proposed in the pull request.
• Add unit tests if applicable.
• Update documentation if applicable.
• Add a note in the CHANGELOG.md if applicable.
• Sign the Google CLA.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (c5f0b61) 79.04% compared to head (ea34b7e) 79.04%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1462   +/-   ##
=======================================
  Coverage   79.04%   79.04%           
=======================================
  Files          15       15           
  Lines         902      902           
=======================================
  Hits          713      713           
  Misses        138      138           
  Partials       51       51