[SPARK-14498][ML][PYTHON][SQL] Many cleanups to ML and ML-related docs

## What changes were proposed in this pull request?

Cleanups to documentation.  No changes to code.
* GBT docs: Move Scala doc for private object GradientBoostedTrees to public docs for GBTClassifier,Regressor
* GLM regParam: needs doc saying it is for L2 only
* TrainValidationSplitModel: add .. versionadded:: 2.0.0
* Rename “_transformer_params_from_java” to “_transfer_params_from_java”
* LogReg Summary classes: “probability” col should not say “calibrated”
* LR summaries: coefficientStandardErrors —> document that intercept stderr comes last.  Same for t,p-values
* approxCountDistinct: Document meaning of “rsd" argument.
* LDA: note which params are for online LDA only

## How was this patch tested?

Doc build

Author: Joseph K. Bradley <joseph@databricks.com>

Closes #12266 from jkbradley/ml-doc-cleanups.

1 files changed, 1 insertions, 1 deletions

diff --git a/python/pyspark/ml/classification.py b/python/pyspark/ml/classification.py
index d98919b3c6..e64c7a392b 100644
--- a/python/pyspark/ml/classification.py
+++ b/python/pyspark/ml/classification.py
@@ -291,7 +291,7 @@ class LogisticRegressionSummary(JavaCallable):
     @since("2.0.0")
     def probabilityCol(self):
         """
-        Field in "predictions" which gives the calibrated probability
+        Field in "predictions" which gives the probability
         of each class as a vector.
         """
         return self._call_java("probabilityCol")