Shopsys: The docs are missing FAQ section

[vitek-rostislav]

What is happening

There is much information missing from our documentation. It is true that we are planning to document many features but it might take a while so creating the FAQ section could bring the developers a great value for less effort. There are already things that could be described in a sentence or two and therefore could be explained in such section...E.g. (thanks to @pk16011990 for reporting):

• What are data fixtures good for?
• How to perform a change of URL (e.g. when swithćhing application to production)
• How to use migrations and why the developers should use shopsys:migrations:generate instead of the default Doctrine one
• what are the diff versions of coding standards check commands and what are their limits
• is the application https ready or does it need some extra setting?
• what about translations and language constants export and import?
• what about deploy and production server setting?

I believe we could come up with a few more others, based on consultation with White and Pink team or based on questions that were asked on slack for example.

Expected result

There is a FAQ section in the docs that briefly answers various common questions and makes Shopsys Framework usage clearer. Even if there are already more descriptive information on a given question, the FAQ could link to the separate article at least to make the information more reachable.

[LukasHeinz]

Another one:

• how can I install project with Czech administration?

[vitek-rostislav]

Another one - what are the differences between "listable", "sellable", "offered" and "visible" products?

[PetrHeinz]

Visibility of products and categories should be explained as well (and the calculated_* convention for materialized data)

[vitek-rostislav]

Another question - how do I change the environment? - files PRODUCTION, DEVELOPMENT, and TEST. Related PR #546

[PetrHeinz]

Maybe a remainder that phing cron should be executed every 5 minutes to run background jobs?
The only mentions in the docs are currently in the article about phing targets and in the production installation guide.