feat(youtube-player): Add documentation README (#16925)

Author: Nathan Tate

src/youtube-player/BUILD.bazel

@@ -3,7 +3,6 @@ package(default_visibility = ["//visibility:public"])
 load("//:packages.bzl", "ROLLUP_GLOBALS")
 load(
     "//tools:defaults.bzl",
-    "markdown_to_html",
     "ng_module",
     "ng_package",
     "ng_test_library",
@@ -54,11 +53,6 @@ ng_web_test_suite(
     deps = [":unit_test_sources"],
 )
 
-markdown_to_html(
-    name = "overview",
-    srcs = [":youtube-player.md"],
-)
-
 filegroup(
     name = "source-files",
     srcs = glob(["**/*.ts"]),

src/youtube-player/README.md

@@ -0,0 +1,60 @@
+# Angular YouTube Player component
+
+This component provides a simple angular wrapper around the embed [YouTube player API](https://developers.google.com/youtube/iframe_api_reference). File any bugs against the [angular/components repo](https://github.com/angular/components/issues).
+
+## Installation
+
+To install, run `npm install @angular/youtube-player`.
+
+## Usage
+
+Follow the following instructions for setting up the YouTube player component:
+
+- First, follow the [instructions for installing the API script](https://developers.google.com/youtube/iframe_api_reference#Getting_Started).
+- Then make sure the API is available before bootstraping the YouTube Player component.
+- Provide find the video id by extracting it from the video URL.
+
+## Example
+
+If your video is found at https://www.youtube.com/watch?v=PRQCAL_RMVo, then your video id is `PRQCAL_RMVo`.
+
+```typescript
+// example-module.ts
+import {CommonModule} from '@angular/common';
+import {NgModule} from '@angular/core';
+import {YouTubePlayerModule} from '@angular/youtube-player';
+import {YoutubePlayerExample} from './example-component';
+
+@NgModule({
+  imports: [
+    // Needed for ngIf directive.
+    CommonModule,
+    YouTubePlayerModule,
+  ],
+  declarations: [YoutubePlayerExample],
+})
+export class YoutubePlayerExampleModule {
+}
+
+// example-component.ts
+@Component({
+  moduleId: module.id,
+  template: '<youtube-player videoId="PRQCAL_RMVo" />',
+  selector: 'youtube-player-example',
+})
+class YoutubePlayerExample implements OnInit {
+  onInit() {
+    // This code loads the IFrame Player API code asynchronously, according to the instructions at
+    // https://developers.google.com/youtube/iframe_api_reference#Getting_Started
+    const tag = document.createElement('script');
+
+    tag.src = "https://www.youtube.com/iframe_api";
+    document.body.appendChild(tag);
+  }
+}
+
+```
+
+## API
+
+Check out the [source](./youtube-player.ts) to read the API.