Update context-and-timeout.md (#114)

Author: andrew-field

context-and-timeout.md

@@ -34,7 +34,7 @@ pageWithCancel.MustNavigate("http://github.com")
 pageWithCancel.MustElement("body")  
 ```
 
-We use the `page.Context` to create a shallow clone of the `page`. Whenever we call the `cancel`, the all sub operations
+We use the `page.Context` to create a shallow clone of the `page`. Whenever we call the `cancel`, all the sub operations
 triggered by the `pageWithCancel` will be canceled, it can be any operation, not just `MustNavigate`.
 The origin `page` won't be affected, if we use it to call operations they won't be cancelled.