The WebApplicationBuilder change looks good. I'm not certain about the second second paragraph of the change - whether we should actually remove the extensions note or not.

@halter73 should it be removed or should it stay as is?

The second paragraph doesn't make much sense in the "Install the preview site extension" section.

At some point, we should probably mention the "ASP.NET Core Logging Integration" site extension which is the actual thing installed by VS that "enables additional functionality for ASP.NET Core on Azure App Services, such as enabling Azure logging", but what's currently there looks wrong. And since VS adds this automatically, documentation suggesting adding it manually should probably be in the "Publish with the CLI" section rather than the overview.

And this doesn't make sense in the context of manually installing a preview "ASP.NET Core {Version} Runtime" site extension which doesn't add additional functionality at all. It's necessary when deploying non-self-contained builds relying on preview runtimes with or without VS. Otherwise, you'll get a "HTTP Error 500.31 - ANCM Failed to Find Native Dependencies"