a FAQ list for influxdb-java

[lxhoan]

Motivation:
influxdb-java users normally will raise a new issue in case they have question. We have seen multiple question-based issues.

We also have a lot of discussion (in form of question-answer in emails, PR timeline conversions) which deserves to record

So I think it's worth collecting those common/valued information to a separate FAQ for later references

This FAQ can be apart of or linked from README.md

The format we follow the one is used by influxdb server
https://docs.influxdata.com/influxdb/v1.5/troubleshooting/frequently-asked-questions/

[ivankudibal]

Functionality

1. Is the batch part of the client thread safe?
2. If multiple threads are accessing it, are they all adding Points to the same batch?
3. And if so, is there a single thread in the background that is emptying batch to the server?
4. If there is an error during this background process, is it propagated to the rest of the client?

Security
One of the questions to be added here: is default config security setup TLS 1.2?