Docs: Update DOC and Getting started guide

[fkolar]

I'm submitting a...

[ ] Regression (a behavior that used to work and stopped working in a new release)
[ ] Bug report  
[ ] Performance issue
[ ] Feature request
[ X] Documentation issue or request
[ ] Support request => Please do not submit support request here, instead see https://github.com/angular/angular/blob/master/CONTRIBUTING.md#question
[ ] Other... Please describe:

Current behavior

Develop new interactive application (tutorial) with a playground, where it can guide a developer thru the whole development process. Playground let;s you play with the rules. For this we can use code mirror to create custom enviornment. It could be similar to: https://rxviz.com/examples/basic-interval

[fkolar]

https://github.com/ngx-meta/rules/wiki/Playground-App-Ideas