Documentation website improvements

### Issue type

**I'm submitting a ...** (check one with "x")

* [ ] bug report
* [x] feature request

### Issue description
* [x] Separate page into the following tabs: `Overview`, `Themes`, `API`, `Examples`
* [x] Create an example module (split existing playground on tests and examples)
* [x] Example renderer component (just render)
* [x] Code snippets renderer component (basic, peace of code from a file)
* [x] Revert simple inline example parser
* [x] Theme swither from examples
* [x] Code snippets AKA Github
* [x] Design update @nnixaa
* [x] Add missed examples, refactor playground
* [ ] Add examples into MD
- [x] Layout @nnixaa
- [x] Sidebar @nnixaa
- [x] Menu @nnixaa
- [x] Card @nnixaa
- [x] Flip Card @nnixaa
- [x] Reveal Card @nnixaa
- [x] Search @nnixaa
- [x] Tabs @nnixaa
- [x] Actions @nnixaa
- [x] User (Avatar) @nnixaa
- [x] Checkbox @Tibing
- [x] Badge @nnixaa
- [x] Popover @Tibing
- [x] Context Menu @Tibing
- [x] Auth @nnixaa _blocked by examples in MD_
- [x] Secutrity @nnixaa _blocked by examples in MD_
- [x] Theming @nnixaa _blocked by examples in MD_
- [x] RTL @yggg _blocked by examples in MD_
* [ ] Stackblitz opener
* [ ] Add documentation structure types, use typings provided by prsr
* [ ] Stacked example to be possible to start from code view @Tibing

TBD