Move styles from sample.css to heroes.component.css, document changes to heroes.component.css in the tutorial.

Edited tutorial to reflect the removal of `sample.css` and the change to `heroes.component.css`.
Remove reference to `/public/docs/_examples/toh-6/ts/index.css` from `/public/docs/_examples/toh-6/ts/index.html`.

Author: Adam-Meisen

public/docs/_examples/toh-6/ts/app/heroes.component.css

@@ -1,3 +1,4 @@
+/* #docregion */
 .selected {
   background-color: #CFD8DC !important;
   color: white;
@@ -57,3 +58,10 @@ button {
 button:hover {
   background-color: #cfd8dc;
 }
+/* #docregion additions */
+.error {color:red;}
+button.delete-button{
+  float:right;
+  background-color: gray !important;
+  color:white;
+}

public/docs/_examples/toh-6/ts/index.html

@@ -6,7 +6,6 @@
     <meta name="viewport" content="width=device-width, initial-scale=1">
 
     <link rel="stylesheet" href="styles.css">
-    <link rel="stylesheet" href="sample.css">
 
     <!-- Polyfill(s) for older browsers -->
     <script src="node_modules/core-js/client/shim.min.js"></script>

public/docs/_examples/toh-6/ts/sample.css

@@ -316,7 +316,9 @@ block add-new-hero-via-detail-comp
   The user can *delete* an existing hero by clicking a delete button next to the hero's name.
   Add the following to the heroes component HTML right after the hero name in the repeated `<li>` tag:
 +makeExample('app/heroes.component.html', 'delete')
-
+:marked
+  Add the following CSS to the bottom of `heroes.component.css`.
++makeExcerpt('toh-6/ts/app/heroes.component.css', 'additions', '')(format=".")
 :marked
   Now let's fix-up the `HeroesComponent` to support the *add* and *delete* actions used in the template.
   Let's start with *add*.
@@ -548,7 +550,6 @@ block filetree
       .file typings ...
       .file index.html
       .file package.json
-      .file sample.css (new)
       .file styles.css
       .file systemjs.config.json
       .file tsconfig.json
@@ -573,20 +574,20 @@ block file-summary
     `toh-6/ts/app/app.component.ts,
      toh-6/ts/app/heroes.component.ts,
      toh-6/ts/app/heroes.component.html,
+     toh-6/ts/app/heroes.component.css,
      toh-6/ts/app/hero-detail.component.ts,
      toh-6/ts/app/hero-detail.component.html,
      toh-6/ts/app/hero.service.ts,
-     toh-6/ts/app/in-memory-data.service.ts,
-     toh-6/ts/sample.css`,
+     toh-6/ts/app/in-memory-data.service.ts`,
     null,
     `app.comp...ts,
      heroes.comp...ts,
      heroes.comp...html,
+     heroes.comp...css,
      hero-detail.comp...ts,
      hero-detail.comp...html,
      hero.service.ts,
-     in-memory-data.service.ts,
-     sample.css`
+     in-memory-data.service.ts`
   )
 
   +makeTabs(