[MINOR][DOCS] s/It take/It takes/g

[jkremser]

What changes were proposed in this pull request?

Fixing three small typos in the docs, in particular:

It take a RDD -> It takes an RDD (twice)

It take an JavaRDD -> It takes a JavaRDD

I didn't create any Jira issue for this minor thing, I hope it's ok.

How was this patch tested?

visually by clicking on 'preview'

[srowen]

That's OK. It'd be ideal to try to find more typos at once if you can -- a quick spell check can turn up more. No need to get all of them but helps avoid PRs for fixing one at a time.

[SparkQA]

Test build #4032 has finished for PR 20108 at commit daae351.

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

[srowen]

This time I'll just merge it.