docs(page_objects): Remove unnecessary "await" and "async" (#4732)

* docs(page_objects): Remove unnecessary "await" and "async"

Author: Jon Hermansen

docs/page-objects.md

@@ -60,8 +60,8 @@ var AngularHomepage = function() {
     await nameInput.sendKeys(name);
   };
 
-  this.getGreetingText = async function() {
-    return await greeting.getText();
+  this.getGreetingText = function() {
+    return greeting.getText();
   };
 
   // Not async, returns the element