Create interactive "Getting Started"

[stalniy]

Requirements:

• replace all examples with interactive ones (from codepen, or something that supports files/directories and console output)
• what is ability, rules
• how to map actions and subjects to real world app (Really hard to grasp the concepts as a newbie #135)
• how to move to roles and recommendations for managing abilities on UI

Update: some questions to think when making this - #209 (comment)

Check also #204

[stalniy]

#191 another issue with wrong usage

[stalniy]

documentation is in process of big rewrite for 4.x release, it should be beginner friendly with a lot of explanations. I don't see the good way to embed interactive examples. So, I will create few scrimba tutorials for some parts of documentation later

For the work here is done, the rest can be tracked in #193