fixes broken example for "weighted mean of more than two colors"

[alex-s-gardner]

old example no longer works

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.75%. Comparing base (3e362e3) to head (a251ec1).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #571   +/-   ##
=======================================
  Coverage   96.75%   96.75%           
=======================================
  Files           9        9           
  Lines        1296     1296           
=======================================
  Hits         1254     1254           
  Misses         42       42           

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[kimikage]

When was it deprecated in the first place?
Since I'm now away from Colors.jl, I don't know where that discussion took place.

[alex-s-gardner]

I'm not sure deprecated is the right description. Changing title to fixes "broken" example

[kimikage]

How did you determine that it was broken?
The document generation passes even without this PR.

And if there is no consensus on the deprecation, we should consider whether we can fix the implementation before updating the documentation.