message: docs(core): fix `ViewChildren` code examples to avoid TS error
  Add a non-null assertion (`!`) in `ViewChildren` code examples to avoid
  a TypeScript error due to uninitialized property.
  Fixes
  PR Close
diff: @@ -337,9 +337,9 @@ export interface ViewChildrenDecorator {
  * * A template reference variable as a string (e.g. query `<my-component #cmp></my-component>`
  * with `@ViewChildren('cmp')`)
  * * Any provider defined in the child component tree of the current component (e.g.
  - * `@ViewChildren(SomeService) someService: SomeService`)
  - * * Any provider defined through a string token (e.g. `@ViewChildren('someToken') someTokenVal:
  - * any`)
  + * `@ViewChildren(SomeService) someService!: SomeService`)
  + * * Any provider defined through a string token (e.g. `@ViewChildren('someToken')
  + * someTokenVal!: any`)
  * * A `TemplateRef` (e.g. query `<ng-template></ng-template>` with `@ViewChildren(TemplateRef)
  * template;`)
  *
  