Update painting_in_the_world.md

[ljhwang]

Extensive editing for clarity. Please review carefully. No guarantee I did not introduce additional typos!

Feel free to edit.

[MFraters]

I found one typo! Otherwise looks good to me.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (dfbb30b) 93.11% compared to head (7ddbbe3) 92.54%.
Report is 8 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #623      +/-   ##
==========================================
- Coverage   93.11%   92.54%   -0.58%     
==========================================
  Files          92       92              
  Lines        6334     6369      +35     
==========================================
- Hits         5898     5894       -4     
- Misses        436      475      +39     

see 3 files with indirect coverage changes

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[github-actions]

Benchmark	Main	Feature	Difference (99.9% CI)
Slab interpolation simple none	1.011 ± 0.004 (s=449)	1.013 ± 0.005 (s=443)	+0.1% .. +0.3%
Slab interpolation curved simple none	1.018 ± 0.004 (s=442)	1.018 ± 0.005 (s=445)	-0.0% .. +0.2%
Spherical slab interpolation simple none	1.168 ± 0.007 (s=380)	1.168 ± 0.007 (s=393)	-0.1% .. +0.1%
Slab interpolation simple curved CMS	1.060 ± 0.004 (s=449)	1.057 ± 0.004 (s=404)	-0.4% .. -0.2%
Spherical slab interpolation simple CMS	1.546 ± 0.009 (s=281)	1.543 ± 0.009 (s=304)	-0.4% .. -0.0%
Spherical fault interpolation simple none	1.165 ± 0.011 (s=396)	1.165 ± 0.011 (s=379)	-0.2% .. +0.2%
Cartesian min max surface	2.310 ± 0.017 (s=185)	2.312 ± 0.026 (s=207)	-0.2% .. +0.4%
Spherical min max surface	7.193 ± 0.023 (s=60)	7.209 ± 0.028 (s=67)	+0.0% .. +0.4%