[BEAM-6574] Inline description of CSV formats

[kennknowles]

A few reasons for this:

• simpler to just read it, as a user
• SQL docs should be uncoupled as possible from Javadocs
• there's plenty of formats that are actually not such a big deal to list
• there was a 404 because the javadoc for CSVFormat was down.

---

Follow this checklist to help us incorporate your contribution quickly and easily:

• Format the pull request title like [BEAM-XXX] Fixes bug in ApproximateQuantiles, where you replace BEAM-XXX with the appropriate JIRA issue, if applicable. This will automatically link the pull request to the issue.
• If this contribution is large, please file an Apache Individual Contributor License Agreement.

It will help us expedite review of your Pull Request if you tag someone (e.g. @username) to look at it.

Post-Commit Tests Status (on master branch)

Lang	SDK	Apex	Dataflow	Flink	Gearpump	Samza	Spark
Go		---	---	---	---	---	---
Java
Python		---			---	---	---

[akedin]

LGTM, yes