Add Validated.validNel

[edmundnoble]

Present as a syntax enrichment already.

[codecov-io]

Codecov Report

Merging #1658 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #1658      +/-   ##
==========================================
+ Coverage   93.33%   93.33%   +<.01%     
==========================================
  Files         240      240              
  Lines        3946     3947       +1     
  Branches      136      137       +1     
==========================================
+ Hits         3683     3684       +1     
  Misses        263      263

Impacted Files	Coverage Δ
core/src/main/scala/cats/data/Validated.scala	100% <100%> (ø)	⬆️

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[ceedubs]

Thanks @edmundnoble. 👍 to this change, but it looks like there are merge conflicts. Also, while this change is trivial, we should probably hit it from a code coverage perspective. Maybe just an sbt-doctest example of using it?

[edmundnoble]

Oof. What is in my master branch? I'll add a doctest and fix the conflicts.

[edmundnoble]

@ceedubs Should be good now, after CI.

[ceedubs]

👍 wonderful thanks @edmundnoble