docs(material/chips): change image alt

change image alts from "shiba1 image" to "Photo of a Shiba Inu"

Author: AlirezaEbrahimkhani

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

@@ -1,19 +1,19 @@
 <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"/>
+        <img src="https://material.angular.io/assets/img/examples/shiba1.jpg" alt="Photo of a Shiba Inu"/>
     </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"/>
+        <img src="https://material.angular.io/assets/img/examples/shiba1.jpg" alt="Photo of a Shiba Inu"/>
     </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"/>
+        <img src="https://material.angular.io/assets/img/examples/shiba1.jpg" alt="Photo of a Shiba Inu"/>
     </mat-chip-avatar>
     Dog three
   </mat-chip>