docs(popover) Fix variable undefined errors (#15543)

* Update angular.md

Fix `event` undefined error

* Update javascript.md

Fix event undefined error

core/src/components/popover/usage/angular.md

@@ -14,7 +14,7 @@ export class PopoverExample {
   async presentPopover(ev: any) {
     const popover = await this.popoverController.create({
       component: PopoverComponent,
-      event: event,
+      event: ev,
       translucent: true
     });
     return await popover.present();

core/src/components/popover/usage/javascript.md

@@ -6,7 +6,7 @@ async function presentPopover(ev) {
   const popover = await popoverController.create({
     component: 'popover-example-page',
     translucent: true
-    event,
+    event: ev,
   });
   return await popover.present();
 }