demos: Update usage.html, change string values of 'true' to proper boolean values (#1897)

Author: dgoudie

demos/src/app/components/dialog-demo/usage.html

@@ -5,8 +5,8 @@ <h3 class="demo-content__headline">Usage</h3>
   <code class="docs-markdown-code">MdcDialogRef</code>:
 
   <pre><code highlight="let dialogRef = dialog.open(UserProfileComponent, {
-  clickOutsideToClose: 'true',
-  escapeToClose: 'true',
+  clickOutsideToClose: true,
+  escapeToClose: true,
 });"></code></pre>
 
   The <code class="docs-markdown-code">MdcDialogRef</code> provides a handle on the opened dialog. It can be used to
@@ -81,4 +81,4 @@ <h3 class="demo-content__headline">Configuring dialog content via entryComponent
   bootstrap: [AppComponent]
 })
 export class AppModule {}"></code></pre>
-</div>
+</div>