Reduce basic README size

[amourzenkov-sc]

Meta-Info	Value
ExtProjectId	JCPROC-01
Original Estimation	4h
Remaining Estimation	0h

Restructure README in the following way:

1. "Getting Started" section has minimal configuration and uses react-crudeditor in the simplest way possible.
2. "Usecases" section has subsections for typical situations a user meets.
3. Advanced sections are moved out of README.