[MINOR][DOCS] Fix all typos in markdown files of doc and similar patterns in other comments

[dongjoon-hyun]

What changes were proposed in this pull request?

This PR tries to fix all typos in all markdown files under docs module,
and fixes similar typos in other comments, too.

How was the this patch tested?

manual tests.

[dongjoon-hyun]

Hi, @rxin .
I finished reviewing all files under the docs module and related stuff.
I think it's all typos for now. Thank you again.

[rxin]

LGTM pending tests.

[srowen]

Nice. That's a lot of

[SparkQA]

Test build #2565 has finished for PR 11300 at commit 86aa742.

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

[srowen]

merged to master

[dongjoon-hyun]

Thank you, @srowen and @rxin !