[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, 9 insertions, 0 deletions

diff --git a/python/pyspark/ml/regression.py b/python/pyspark/ml/regression.py
index f6c5d130dd..1c18df3b27 100644
--- a/python/pyspark/ml/regression.py
+++ b/python/pyspark/ml/regression.py
@@ -331,6 +331,9 @@ class LinearRegressionSummary(JavaCallable):
         Standard error of estimated coefficients and intercept.
         This value is only available when using the "normal" solver.
 
+        If :py:attr:`LinearRegression.fitIntercept` is set to True,
+        then the last element returned corresponds to the intercept.
+
         .. seealso:: :py:attr:`LinearRegression.solver`
         """
         return self._call_java("coefficientStandardErrors")
@@ -342,6 +345,9 @@ class LinearRegressionSummary(JavaCallable):
         T-statistic of estimated coefficients and intercept.
         This value is only available when using the "normal" solver.
 
+        If :py:attr:`LinearRegression.fitIntercept` is set to True,
+        then the last element returned corresponds to the intercept.
+
         .. seealso:: :py:attr:`LinearRegression.solver`
         """
         return self._call_java("tValues")
@@ -353,6 +359,9 @@ class LinearRegressionSummary(JavaCallable):
         Two-sided p-value of estimated coefficients and intercept.
         This value is only available when using the "normal" solver.
 
+        If :py:attr:`LinearRegression.fitIntercept` is set to True,
+        then the last element returned corresponds to the intercept.
+
         .. seealso:: :py:attr:`LinearRegression.solver`
         """
         return self._call_java("pValues")