Update Windows instructions of examples

[Tiryoh]

🦟 Bug fix

Fixes #

Summary

apply #631 to other examples

• gz-math: Triangle example gazebo_test_cases#1369
• gz-math: Vector example gazebo_test_cases#1372
• gz-math: Angle example gazebo_test_cases#1366

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.