[SPARK-11445][DOCS]Replaced example code in mllib-ensembles.md using include_example

[rishabhbhardwaj]

I have made the required changes and tested.
Kindly review the changes.

[mengxr]

ok to test

[mengxr]

@yinxusen Could you help review this PR?

[yinxusen]

Add a blank line below here.

[rishabhbhardwaj]

@yinxusen Thanks for your comments.Have made the required changes in the files you pointed and others also.Please review.

[SparkQA]

Test build #44872 has finished for PR 9407 at commit a71e99b.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[yinxusen]

def main(args: Array[String]): Unit = {

[yinxusen]

blank line

[yinxusen]

@rishabhbhardwaj One more thing, all of your Python code files have no definition of sc. Try to run the example after adding it as a single code file.

[rishabhbhardwaj]

@yinxusen Made the changes.Also ran the python files and they are working fine.Thanks for your inputs.WIll keep these points in mind from next time.

[SparkQA]

Test build #44883 has finished for PR 9407 at commit 29a8067.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):\n * public class JavaGradientBoostingClassificationExample\n * public class JavaGradientBoostingRegressionExample\n * public class JavaRandomForestClassificationExample\n * public class JavaRandomForestRegressionExample\n

[yinxusen]

@mengxr LGTM

[mengxr]

Merged into master and branch-1.6. Thanks!