[MINOR][ML] Fix comments in LSH Examples and Python API

[Yunni]

What changes were proposed in this pull request?

Remove org.apache.spark.examples. in
Add slash in one of the python doc.

How was this patch tested?

Run examples using the commands in the comments.

[SparkQA]

Test build #73603 has finished for PR 17104 at commit d6d1407.

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

[srowen]

Does it not work? I thought the full qualified name was fine.

[Yunni]

@srowen The full name works. Just want to make the comments shorter so that it's easier to read.

[yanboliang]

LGTM, merged into master. Thanks.