The `useEffect` has two parameters:
* The `effect` function
* The `computeDependencies` function
The `effect` function always take as parameters the result
of the `computeDependencies` function.
Expliciting this allows to better understand the `useEffect`
behaviour and the following example in the doc:
```
useEffect(
(el) => el && el.focus(),
() => [ref.el]
);
```
including:
- add a link to the tutorial in the main readme page
- remove learning page on 'env', move content on reference page
- add dynamic sub components section in component page
- add reference page on props
- split qweb page into engine/language pages
- move t-key information into qweb language page
Florent Dardenne - dafl@odoo