Add info on how components are loaded (especially useful for Toast & Alert ones)

**URL**
The URL at which the content is missing or inaccurate:
- Globally at: https://ionicframework.com/docs/components
- Or in the Toast & Alert component at: https://ionicframework.com/docs/api/toast, https://ionicframework.com/docs/api/alert

**What is missing or inaccurate about the content on this page?**
I was testing that an app that I'm developing was working correctly when the user's device does not have an internet connection, and for that I'm displaying a toast when a request fails because he does not have an internet connection. But this toast was never displaying and every time I was getting an error in the developer console of my browser. I did some research and figure out that components are lazy loaded and that was the cause of the problem (see the explanation here: https://github.com/ionic-team/ionic-framework/issues/17450#issuecomment-628223724).

Hence, this would be really cool to add this explanation on the Ionic website to inform people that you have to preload components that you want to display when the user's device goes offline.

Start with the components documentation and the Toast and Alert API pages linked in the issue. Explain that components are lazy loaded and document how to preload components needed when an app is offline; the linked Ionic Framework discussion provides the background to verify the wording.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.