[SPARK-7916] [MLlib] MLlib Python doc parity check for classification and regression

[yanboliang]

Check then make the MLlib Python classification and regression doc to be as complete as the Scala doc.

[SparkQA]

Test build #33663 has finished for PR 6460 at commit 3eaf6ad.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):
  • class KryoSerializationStream(
  • class KryoDeserializationStream(

[yanboliang]

The length of docstring line for PEP8 standard is 72, so truncate too long line.

[SparkQA]

Test build #33805 has finished for PR 6460 at commit ce2a43e.

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

[jkbradley]

This should not say "with no regularization." It looks like this is a difference between the Python & Scala APIs.

[jkbradley]

@yanboliang Thanks for adding this doc! With so many Python users, this should be very helpful.

[SparkQA]

Test build #34932 has finished for PR 6460 at commit 6dc4d99.

• This patch fails Spark unit tests.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #34968 has finished for PR 6460 at commit f8deda4.

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

[jkbradley]

This LGTM I'll merge it into master and branch-1.4

@yanboliang Thanks for the PR, and sorry about the delay in merging! We can update the docs on the website at any time, thankfully, so this should be able to go up once some other updates get in as well.