Improvements for documentation

[AnastasiiaSergienko]

I used new documentation and wrote down some things that were missing or that I would like to have:

Creating dialect part:

1. I didn't find information about how to implement applyQuote method and SUPPORTED_PROPERTIES list.

Deploying adapter:

1. It would be really nice to have a completed demo-example of registering adapter, connecting and creating VS somewhere in the documentation. Something similar to that one we used in the presentation.
2. Remote logging is still quite hard to deal with. I didn't manage to start logging.

API

I found a few inaccuracies in the Virtual Schema API Documentation while using it.

Missing literal_interval json example here: https://github.com/exasol/virtual-schemas/tree/master/doc#literal

I discovered that "type": "predicate_equals" doesn't really work in our implementation, but "type": "predicate_equal" works fine. We need to fix the documentation or the implementation. You can find it here: https://github.com/exasol/virtual-schemas/tree/master/doc#predicates

The same for "predicate_notequals".

The same for "predicate_lessequals".

Missing predicate_is_null and predicate_is_not_null here: https://github.com/exasol/virtual-schemas/tree/master/doc#predicates

[AnastasiiaSergienko]

Unfinished part of the ticket moved to a new issue: #276
It will be finished on the new branch.
This issue will be closed.