Ignition -> Gazebo

[jennuine]

🦟 Bug fix

Part of:

• Increase test coverage gz-sim#1575
• Rename Ignition to Gazebo gazebo-tooling/release-tools#698

Summary

Updated links and naming in README.md

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 #94 (35032d1) into ign-plugin1 (9d933de) will not change coverage.
The diff coverage is n/a.

@@             Coverage Diff              @@
##           ign-plugin1      #94   +/-   ##
============================================
  Coverage        99.82%   99.82%           
============================================
  Files               15       15           
  Lines              584      584           
============================================
  Hits               583      583           
  Misses               1        1           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 9d933de...35032d1. Read the comment docs.