[SPARK-18447][DOCS] Fix the markdown for `Note:`/`NOTE:`/`Note that` across Python API documentation

## What changes were proposed in this pull request?

It seems in Python, there are

- `Note:`
- `NOTE:`
- `Note that`
- `.. note::`

This PR proposes to fix those to `.. note::` to be consistent.

**Before**

<img width="567" alt="2016-11-21 1 18 49" src="https://cloud.githubusercontent.com/assets/6477701/20464305/85144c86-af88-11e6-8ee9-90f584dd856c.png">

<img width="617" alt="2016-11-21 12 42 43" src="https://cloud.githubusercontent.com/assets/6477701/20464263/27be5022-af88-11e6-8577-4bbca7cdf36c.png">

**After**

<img width="554" alt="2016-11-21 1 18 42" src="https://cloud.githubusercontent.com/assets/6477701/20464306/8fe48932-af88-11e6-83e1-fc3cbf74407d.png">

<img width="628" alt="2016-11-21 12 42 51" src="https://cloud.githubusercontent.com/assets/6477701/20464264/2d3e156e-af88-11e6-93f3-cab8d8d02983.png">

## How was this patch tested?

The notes were found via

```bash
grep -r "Note: " .
grep -r "NOTE: " .
grep -r "Note that " .
```

And then fixed one by one comparing with API documentation.

After that, manually tested via `make html` under `./python/docs`.

Author: hyukjinkwon <gurwls223@gmail.com>

Closes #15947 from HyukjinKwon/SPARK-18447.

1 files changed, 16 insertions, 16 deletions

diff --git a/python/pyspark/ml/regression.py b/python/pyspark/ml/regression.py
index 385391ba53..b42e807069 100644
--- a/python/pyspark/ml/regression.py
+++ b/python/pyspark/ml/regression.py
@@ -245,9 +245,9 @@ class LinearRegressionSummary(JavaWrapper):
         .. seealso:: `Wikipedia explain variation \
         <http://en.wikipedia.org/wiki/Explained_variation>`_
 
-        Note: This ignores instance weights (setting all to 1.0) from
-        `LinearRegression.weightCol`. This will change in later Spark
-        versions.
+        .. note:: This ignores instance weights (setting all to 1.0) from
+            `LinearRegression.weightCol`. This will change in later Spark
+            versions.
         """
         return self._call_java("explainedVariance")
 
@@ -259,9 +259,9 @@ class LinearRegressionSummary(JavaWrapper):
         corresponding to the expected value of the absolute error
         loss or l1-norm loss.
 
-        Note: This ignores instance weights (setting all to 1.0) from
-        `LinearRegression.weightCol`. This will change in later Spark
-        versions.
+        .. note:: This ignores instance weights (setting all to 1.0) from
+            `LinearRegression.weightCol`. This will change in later Spark
+            versions.
         """
         return self._call_java("meanAbsoluteError")
 
@@ -273,9 +273,9 @@ class LinearRegressionSummary(JavaWrapper):
         corresponding to the expected value of the squared error
         loss or quadratic loss.
 
-        Note: This ignores instance weights (setting all to 1.0) from
-        `LinearRegression.weightCol`. This will change in later Spark
-        versions.
+        .. note:: This ignores instance weights (setting all to 1.0) from
+            `LinearRegression.weightCol`. This will change in later Spark
+            versions.
         """
         return self._call_java("meanSquaredError")
 
@@ -286,9 +286,9 @@ class LinearRegressionSummary(JavaWrapper):
         Returns the root mean squared error, which is defined as the
         square root of the mean squared error.
 
-        Note: This ignores instance weights (setting all to 1.0) from
-        `LinearRegression.weightCol`. This will change in later Spark
-        versions.
+        .. note:: This ignores instance weights (setting all to 1.0) from
+            `LinearRegression.weightCol`. This will change in later Spark
+            versions.
         """
         return self._call_java("rootMeanSquaredError")
 
@@ -301,9 +301,9 @@ class LinearRegressionSummary(JavaWrapper):
         .. seealso:: `Wikipedia coefficient of determination \
         <http://en.wikipedia.org/wiki/Coefficient_of_determination>`
 
-        Note: This ignores instance weights (setting all to 1.0) from
-        `LinearRegression.weightCol`. This will change in later Spark
-        versions.
+        .. note:: This ignores instance weights (setting all to 1.0) from
+            `LinearRegression.weightCol`. This will change in later Spark
+            versions.
         """
         return self._call_java("r2")
 
@@ -822,7 +822,7 @@ class DecisionTreeRegressionModel(DecisionTreeModel, JavaMLWritable, JavaMLReada
             where gain is scaled by the number of instances passing through node
           - Normalize importances for tree to sum to 1.
 
-        Note: Feature importance for single decision trees can have high variance due to
+        .. note:: Feature importance for single decision trees can have high variance due to
               correlated predictor variables. Consider using a :py:class:`RandomForestRegressor`
               to determine feature importance instead.
         """