## What changes were proposed in this pull request?
This PR proposes to relocate the docstrings in modules of examples to the top. Seems these are mistakes. So, for example, the below codes
```python
>>> help(aft_survival_regression)
```
shows the module docstrings for examples as below:
**Before**
```
Help on module aft_survival_regression:
NAME
aft_survival_regression
...
DESCRIPTION
# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements. See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
# the License. You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
...
(END)
```
**After**
```
Help on module aft_survival_regression:
NAME
aft_survival_regression
...
DESCRIPTION
An example demonstrating aft survival regression.
Run with:
bin/spark-submit examples/src/main/python/ml/aft_survival_regression.py
(END)
```
## How was this patch tested?
Manually checked.
Author: hyukjinkwon <gurwls223@gmail.com>
Closes#20416 from HyukjinKwon/module-docstring-example.
b8c32dc573