XML docs for Permutation feature importance for Binary, Multi-class and Ranking trainers.

[codemzs]

towards #3204

[artidoro]

[codecov]

Codecov Report

Merging #3455 into master will decrease coverage by <.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #3455      +/-   ##
==========================================
- Coverage   72.77%   72.77%   -0.01%     
==========================================
  Files         808      808              
  Lines      145449   145452       +3     
  Branches    16244    16244              
==========================================
+ Hits       105844   105846       +2     
- Misses      35186    35188       +2     
+ Partials     4419     4418       -1

Flag	Coverage Δ
#Debug	72.77% <ø> (-0.01%)	⬇️
#production	68.28% <ø> (-0.01%)	⬇️
#test	89.04% <ø> (ø)	⬆️

Impacted Files	Coverage Δ
src/Microsoft.ML.LightGbm/LightGbmCatalog.cs	100% <ø> (ø)	⬆️
...ansforms/PermutationFeatureImportanceExtensions.cs	97.93% <ø> (ø)	⬆️
src/Microsoft.ML.FastTree/TreeTrainersCatalog.cs	94.18% <ø> (ø)	⬆️
src/Microsoft.ML.Maml/MAML.cs	24.75% <0%> (-1.46%)	⬇️
src/Microsoft.ML.Transforms/OneHotHashEncoding.cs	88.09% <0%> (ø)	⬆️
src/Microsoft.ML.Transforms/NormalizerCatalog.cs	84.78% <0%> (ø)	⬆️
src/Microsoft.ML.Transforms/OneHotEncoding.cs	86.07% <0%> (ø)	⬆️
src/Microsoft.ML.Transforms/GcnTransform.cs	77.57% <0%> (+0.1%)	⬆️
...soft.ML.Data/DataLoadSave/Text/TextLoaderCursor.cs	85.11% <0%> (+0.2%)	⬆️
...StandardTrainers/Standard/LinearModelParameters.cs	60.31% <0%> (+0.26%)	⬆️
... and 1 more

[Ivanidzo4ka]

[shmoradims]

    /// the original values for all other features. The evalution metric (e.g. micro-accuracy) is then calculated

typo: evaluation (same typo in all versions) #Closed

---

Refers to: src/Microsoft.ML.Transforms/PermutationFeatureImportanceExtensions.cs:191 in cf3f0ef. [](commit_id = cf3f0ef, deletion_comment = False)

[shmoradims]

    /// <code>ImmutableArray</code> of <code>MulticlassClassificationMetrics</code> objects is returned. See the sample below for an

use cref instead of (which doesn't render correctly):

of

same with all overloads #Closed

---

Refers to: src/Microsoft.ML.Transforms/PermutationFeatureImportanceExtensions.cs:198 in cf3f0ef. [](commit_id = cf3f0ef73259937935fa15f13018803f0b8a6f83, deletion_comment = False)

[shmoradims]