Added macOS source code installation instructions

[ahcorde]

Signed-off-by: Alejandro Hernández ahcorde@gmail.com

🦟 Bug fix

Summary

Added macOS source code installation instructions

Checklist

• Signed all commits for DCO
• Added tests
• Updated documentation (as needed)
• Updated migration guide (as needed)
• 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

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[codecov]

Codecov Report

Merging #297 (3e7208c) into main (653b0fb) will increase coverage by 0.16%.
The diff coverage is 46.03%.

❗ Current head 3e7208c differs from pull request most recent head 25e0c4f. Consider uploading reports for the commit 25e0c4f to get more accurate results

@@            Coverage Diff             @@
##             main     #297      +/-   ##
==========================================
+ Coverage   65.31%   65.47%   +0.16%     
==========================================
  Files          32       32              
  Lines        4621     4686      +65     
==========================================
+ Hits         3018     3068      +50     
- Misses       1603     1618      +15     

Impacted Files	Coverage Δ
include/ignition/gui/GuiEvents.hh	100.00% <ø> (ø)
...interactive_view_control/InteractiveViewControl.cc	16.52% <10.71%> (+2.24%)	⬆️
src/plugins/minimal_scene/MinimalScene.cc	58.92% <32.75%> (-0.54%)	⬇️
src/Conversions.cc	95.00% <78.94%> (-5.00%)	⬇️
src/GuiEvents.cc	100.00% <100.00%> (ø)
src/plugins/scene3d/Scene3D.cc	49.09% <100.00%> (+0.19%)	⬆️

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[jennuine]

LGTM but I don't have a macOS system to test this. Also, should this target an earlier version or at least ign-gui5?