Components: [CdkScrollable] Add more documentation and demo examples

[kukac7]

i'm trying to put together the test of how to put a "scrollspy" together.
but unfortunately i did not find any help in the documentation.

can you expect a user manual?
thanks!

[lishichao1002]

+1

[nerdlich-media]

+1

[mehrdadg11]

+1

[Netherium]

I have implemented 3 possible ways on how to integrate CdkScrollable,
non of which I feel follows best practices or optimization.

• Hardcoded handling of classes with 'nativeElement'
  (best one but dirty)
• Observable but updated with 'ngZone.run()'
  (Works but ngZone.run will trigger unnecessary events in the digest cycle, i.e. 'ObservableMedia')
• Observable but won't update until resize, 'drawer.toggle()' or other events are triggered
  (Cleanest one but will not function properly)

Can we please get a proper example/documentation that will follow best practices and be optimized?

[liuganchen]

监听滚动事件的时候，数据绑定是失效的。
此时比较折中的办法应该是 对 元素直接操作，代码触发angular 的数据视图更改可能会有潜在的风险。

[LayZeeDK]

Example with Sidenav
https://stackoverflow.com/a/50812763/1071200

[karineagredo]

I'm struggling to implement the CdkScrollable feature. Please provide more examples. I'm following the example provided by Sebastian Denis in https://stackoverflow.com/a/50812763/1071200 but always get Data undefined.