docs(material/chips): the ending > tag markers and add description

Change the ending > tag markers to be on the same line as their opening and add more description about chips avatar example

Author: AlirezaEbrahimkhani

src/components-examples/material/chips/chips-avatar/chips-avatar-example.html

@@ -1,20 +1,20 @@
 <mat-chip-list aria-label="Dog selection">
   <mat-chip>
-    <mat-chip-avatar
-      ><img src="https://material.angular.io/assets/img/examples/shiba1.jpg" alt="shiba1 image"
-    /></mat-chip-avatar>
+    <mat-chip-avatar>
+        <img src="https://material.angular.io/assets/img/examples/shiba1.jpg" alt="shiba1 image"/>
+    </mat-chip-avatar>
     Dog one
   </mat-chip>
   <mat-chip color="primary">
-    <mat-chip-avatar
-      ><img src="https://material.angular.io/assets/img/examples/shiba1.jpg" alt="shiba1 image"
-    /></mat-chip-avatar>
+    <mat-chip-avatar>
+        <img src="https://material.angular.io/assets/img/examples/shiba1.jpg" alt="shiba1 image"/>
+    </mat-chip-avatar>
     Dog two
   </mat-chip>
   <mat-chip color="accent">
-    <mat-chip-avatar
-      ><img src="https://material.angular.io/assets/img/examples/shiba1.jpg" alt="shiba1 image"
-    /></mat-chip-avatar>
+    <mat-chip-avatar>
+        <img src="https://material.angular.io/assets/img/examples/shiba1.jpg" alt="shiba1 image"/>
+    </mat-chip-avatar>
     Dog three
   </mat-chip>
 </mat-chip-list>

src/components-examples/material/chips/chips-avatar/chips-avatar-example.ts

@@ -2,6 +2,7 @@ import {Component} from '@angular/core';
 
 /**
  * @title Chips avatar
+ * @description An avatar inside a chip
  */
 @Component({
   selector: 'chips-avatar-example',