[WIP] The Quick Tour

I started with the quick tour, one section is now drafted, 3 to go. I open this PR already, so you can give feedback early.

| Q   | A
| --- | ---
| Doc fix? | no
| New docs? | yes
| Applies to | all
| Fixed Tickets | #244, #246, #245, #247 

## 1.1 changes

 - `doctrine:phpcr:repository:init` can be removed as it's done by `doctrine:phpcr:fixtures:load`