[SPARK-18633][ML][EXAMPLE] Add multiclass logistic regression summary python example and document

## What changes were proposed in this pull request?
Logistic Regression summary is added in Python API. We need to add example and document for summary.

The newly added example is consistent with Scala and Java examples.

## How was this patch tested?

Manually tests: Run the example with spark-submit; copy & paste code into pyspark; build document and check the document.

Author: wm624@hotmail.com <wm624@hotmail.com>

Closes #16064 from wangmiao1981/py.

1 files changed, 8 insertions, 2 deletions

diff --git a/docs/ml-classification-regression.md b/docs/ml-classification-regression.md
index 575959307a..bb9390fd82 100644
--- a/docs/ml-classification-regression.md
+++ b/docs/ml-classification-regression.md
@@ -114,9 +114,15 @@ Continuing the earlier example:
 {% include_example java/org/apache/spark/examples/ml/JavaLogisticRegressionSummaryExample.java %}
 </div>
 
-<!--- TODO: Add python model summaries once implemented -->
 <div data-lang="python" markdown="1">
-Logistic regression model summary is not yet supported in Python.
+[`LogisticRegressionTrainingSummary`](api/python/pyspark.ml.html#pyspark.ml.classification.LogisticRegressionSummary)
+provides a summary for a
+[`LogisticRegressionModel`](api/python/pyspark.ml.html#pyspark.ml.classification.LogisticRegressionModel).
+Currently, only binary classification is supported. Support for multiclass model summaries will be added in the future.
+
+Continuing the earlier example:
+
+{% include_example python/ml/logistic_regression_summary_example.py %}
 </div>
 
 </div>