[SPARK-10669] [DOCS] Link to each language's API in codetabs in ML docs: spark.mllib

In the Markdown docs for the spark.mllib Programming Guide, we have code examples with codetabs for each language. We should link to each language's API docs within the corresponding codetab, but we are inconsistent about this. For an example of what we want to do, see the "ChiSqSelector" section in https://github.com/apache/spark/blob/64743870f23bffb8d96dcc8a0181c1452782a151/docs/mllib-feature-extraction.md
This JIRA is just for spark.mllib, not spark.ml.

Please let me know if more work is needed, thanks a lot.

Author: Xin Ren <iamshrek@126.com>

Closes #8977 from keypointt/SPARK-10669.

1 files changed, 6 insertions, 0 deletions

diff --git a/docs/mllib-isotonic-regression.md b/docs/mllib-isotonic-regression.md
index 6aa881f749..f91a697b31 100644
--- a/docs/mllib-isotonic-regression.md
+++ b/docs/mllib-isotonic-regression.md
@@ -59,6 +59,8 @@ i.e. 4710.28,500.00. The data are split to training and testing set.
 Model is created using the training set and a mean squared error is calculated from the predicted
 labels and real labels in the test set.
 
+Refer to the [`IsotonicRegression` Scala docs](api/scala/index.html#org.apache.spark.mllib.regression.IsotonicRegression) and [`IsotonicRegressionModel` Scala docs](api/scala/index.html#org.apache.spark.mllib.regression.IsotonicRegressionModel) for details on the API.
+
 {% highlight scala %}
 import org.apache.spark.mllib.regression.{IsotonicRegression, IsotonicRegressionModel}
 
@@ -101,6 +103,8 @@ i.e. 4710.28,500.00. The data are split to training and testing set.
 Model is created using the training set and a mean squared error is calculated from the predicted
 labels and real labels in the test set.
 
+Refer to the [`IsotonicRegression` Java docs](api/java/org/apache/spark/mllib/regression/IsotonicRegression.html) and [`IsotonicRegressionModel` Java docs](api/java/org/apache/spark/mllib/regression/IsotonicRegressionModel.html) for details on the API.
+
 {% highlight java %}
 import org.apache.spark.SparkConf;
 import org.apache.spark.api.java.JavaDoubleRDD;
@@ -167,6 +171,8 @@ i.e. 4710.28,500.00. The data are split to training and testing set.
 Model is created using the training set and a mean squared error is calculated from the predicted
 labels and real labels in the test set.
 
+Refer to the [`IsotonicRegression` Python docs](api/python/pyspark.mllib.html#pyspark.mllib.regression.IsotonicRegression) and [`IsotonicRegressionModel` Python docs](api/python/pyspark.mllib.html#pyspark.mllib.regression.IsotonicRegressionModel) for more details on the API.
+
 {% highlight python %}
 import math
 from pyspark.mllib.regression import IsotonicRegression, IsotonicRegressionModel