docs: incorporate review feedback (#26827)

PR Close #26827

packages/common/http/src/interceptor.ts

@@ -16,13 +16,13 @@ import {HttpEvent} from './response';
 /**
  * Intercepts `HttpRequest` or `HttpResponse` and handles them.
  *
- * Most interceptors transforms the outgoing request before passing it to the
+ * Most interceptors transform the outgoing request before passing it to the
  * next interceptor in the chain, by calling `next.handle(transformedReq)`.
- * An interceptor may choose to transform the
+ * An interceptor may transform the
- * response event stream as well, by applying additional Rx operators on the stream
+ * response event stream as well, by applying additional RxJS operators on the stream
  * returned by `next.handle()`.
  *
- * More rarely, an interceptor may choose to handle the request itself completely,
+ * More rarely, an interceptor may handle the request entirely,
  * and compose a new event stream instead of invoking `next.handle()`. This is an
  * acceptable behavior, but keep in mind that further interceptors will be skipped entirely.
  *
@@ -31,11 +31,21 @@ import {HttpEvent} from './response';
  *
  * @publicApi
  *
+ * @see [HTTP Guide](guide/http#intercepting-requests-and-responses)
+ *
+ * @usageNotes
+ *
+ * To use the same instance of `HttpInterceptors` for the entire app, import the `HttpClientModule`
+ * only in your `AppModule`, and add the interceptors to the root application injector .
+ * If you import `HttpClientModule` multiple times across different modules (for example, in lazy
+ * loading modules), each import creates a new copy of the `HttpClientModule`, which overwrites the interceptors
+ * provided in the root module.
+ *
  */
 export interface HttpInterceptor {
   /**
    * * **req**: The outgoing request to handle
-   * * **next**: The next interceptor in the chain
+   * * **next**: The next interceptor in the chain, or the backend if no interceptors in the chain.
    *
    */
   intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>>;