Documentation does not explain what generics represent

#### Documentation Feedback

In docs it would be helpful to have documentaion for declared TS generics.
For example, I open `MatDatepickerInputEvent` [docs](https://material.angular.io/components/datepicker/api#MatDatepickerInputEvent) and see `S` and `D` generics.
And from the docs it's unclear what these `S` and `D` represent!

I think it should be documented similar to as Java does it.
For example, a [docs](https://docs.oracle.com/en/java/javase/15/docs/api/java.base/java/util/function/Function.html) of Java's standard type `Function` contain a section

> Type Parameters:
> T - the type of the input to the function
> R - the type of the result of the function

从 Angular Material datepicker API 文档中的 MatDatepickerInputEvent 条目开始，检查其 TypeScript 声明是如何呈现的。按照所链接的 Java 文档中展示的类型参数风格，记录类型参数 S 和 D 分别代表什么。完成的标准是新贡献者能够通过 API 文档理解这两个泛型。

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