Update Makie plotting method, add recipe for Plots.jl, example + documentation tweaks

[jbisits]

Closes #51

[codecov]

Codecov Report

Merging #56 (b3f114b) into main (33512fa) will decrease coverage by 2.18%.
The diff coverage is 70.37%.

@@            Coverage Diff             @@
##             main      #56      +/-   ##
==========================================
- Coverage   93.89%   91.72%   -2.18%     
==========================================
  Files           2        2              
  Lines         295      302       +7     
==========================================
  Hits          277      277              
- Misses         18       25       +7     

Impacted Files	Coverage Δ
src/oceanvariableconversions.jl	100.00% <ø> (ø)
src/oceanvariabledistributions.jl	86.11% <70.37%> (-3.49%)	⬇️

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[jbisits]

The codecov decrease is just due to the plotting recipe (which works) and the function to convert zeros to NaN for convert_arguments, which also looks to be working so I can live with the small loss of coverage and write a test (not for the recipe) if need be.