docs: Add app shell story.

Author: Brocco

docs/documentation/stories.md

@@ -3,6 +3,7 @@
 # Stories describing how to do more with the CLI
 
  - [1.0 Update](stories/1.0-update)
+ - [App Shell](stories/app-shell)
  - [Asset Configuration](stories/asset-configuration)
  - [Autocompletion](stories/autocompletion)
  - [Configure Hot Module Replacement](stories/configure-hmr)

docs/documentation/stories/app-shell.md

@@ -0,0 +1,54 @@
+<!-- Links in /docs/documentation should NOT have \`.md\` at the end, because they end up in our wiki at release. -->
+
+# App shell
+
+App shell is a way to render a portion of your application via a route at build time. This gives users a meaningful first paint of your application because the browser does not need to initialize any JavaScript, just rendering the HTML.
+
+## Steps
+
+### Step 1: Prepare the application
+
+An application must be set up with routing. This can be accomplished by running:
+```
+ng new my-app --routing
+```
+Or if you have an existing application you can manually add routing by including the RouterModule and defining a `<router-outlet>` within your app.
+
+
+### Step 2: Create the app shell
+```
+ng generate app-shell --client-project my-app --universal-project server-app
+```
+`my-app` is the name of your client application
+`server-app` is the name of the universal (or server) application
+
+After running this command you will notice that the `angular.json` configuration file has been updated. Two new targets were added (and a few other changes):
+```
+"server": {
+  "builder": "@angular-devkit/build-angular:server",
+  "options": {
+    "outputPath": "dist/my-app-server",
+    "main": "src/main.server.ts",
+    "tsConfig": "src/tsconfig.server.json"
+  }
+},
+"app-shell": {
+  "builder": "@angular-devkit/build-angular:app-shell",
+  "options": {
+    "browserTarget": "my-app:build",
+    "serverTarget": "my-app:server",
+    "route": "shell"
+  }
+}
+```
+
+### Step 3: Verify the app is built with the shell content
+
+build with the app shell target
+```
+ng run my-app:app-shell
+```
+
+Verify the build output
+Open dist/app-shell/index.html
+look for text "app-shell works!" which verifies that the app shell route was rendered as part of the output