Fixed cppgetstarted visualization

[ahcorde]

🦟 Bug fix

Summary

The tutorial is not properly render https://gazebosim.org/api/math/7/cppgetstarted.html This should fix the issue.

Checklist

• Signed all commits for DCO
• Added tests
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
• While waiting for a review on your PR, please help review another open pull request to support the maintainers

Note to maintainers: Remember to use Squash-Merge and edit the commit message to match the pull request summary while retaining Signed-off-by messages.

[codecov]

Codecov Report

Merging #505 (e2c6351) into gz-math7 (860c546) will not change coverage.
The diff coverage is n/a.

❗ Current head e2c6351 differs from pull request most recent head 9271a3e. Consider uploading reports for the commit 9271a3e to get more accurate results

@@            Coverage Diff            @@
##           gz-math7     #505   +/-   ##
=========================================
  Coverage     99.70%   99.70%           
=========================================
  Files            77       77           
  Lines          7007     7007           
=========================================
  Hits           6986     6986           
  Misses           21       21           

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