message: docs(core): add API documentation to standalone-related classes
  This commit adds some internal documentation.
  PR Close
diff: @@ -13,7 +13,11 @@ import {OnDestroy} from '../../interface/lifecycle_hooks';
  import {ComponentDef} from '../interfaces/definition';
  import {createEnvironmentInjector} from '../ng_module_ref';
  -// TODO(pk): document
  +/**
  + * A service used by the framework to create instances of standalone injectors. Those injectors are
  + * created on demand in case of dynamic component instantiation and contain ambient providers
  + * collected from the imports graph rooted at a given standalone component.
  + */
  class StandaloneService implements OnDestroy {
  cachedInjectors = new Map<ComponentDef<unknown>, EnvironmentInjector|null>();
  @@ -60,7 +64,12 @@ class StandaloneService implements OnDestroy {
  }
  /**
  - * TODO(pk): documentation
  + * A feature that acts as a setup code for the {@see StandaloneService}.
  + *
  + * The most important responsaibility of this feature is to expose the "getStandaloneInjector"
  + * function (an entry points to a standalone injector creation) on a component definition object. We
  + * go through the features infrastructure to make sure that the standalone injector creation logic
  + * is tree-shakable and not included in applications that don't use standalone components.
  *
  * @codeGenApi
  */
  