docs(virtual-scroll): fix minor typo (#13892)

Author: PowerKiKi

src/material-examples/cdk-virtual-scroll-context/cdk-virtual-scroll-context-example.html

@@ -11,7 +11,7 @@
     <div class="example-item-detail">Count: {{count}}</div>
     <div class="example-item-detail">First: {{first ? 'Yes' : 'No'}}</div>
     <div class="example-item-detail">Last: {{last ? 'Yes' : 'No'}}</div>
-    <div class="example-item-detail">Event: {{even ? 'Yes' : 'No'}}</div>
+    <div class="example-item-detail">Even: {{even ? 'Yes' : 'No'}}</div>
     <div class="example-item-detail">Odd: {{odd ? 'Yes' : 'No'}}</div>
   </div>
 </cdk-virtual-scroll-viewport>