docs: additional application builder SSR conversion information

This change updates the new build system migration guide with additional
information regarding the steps needed to convert an existing SSR project
to use the new integrated SSR capabilities.

aio/content/guide/esbuild.md

@@ -111,15 +111,31 @@ Many of the warnings will provide suggestions on how to remedy that problem.
 If it appears that a warning is incorrect or the solution is not apparent, please open an issue on [GitHub](https://github.com/angular/angular-cli/issues).
 Also, the later sections of this guide provide additional information on several specific cases as well as current known issues.
 
-For applications that are already using SSR, additional manual adjustments to code will be needed to update the SSR server code to support the new integrated SSR capabilities.
+For applications new to SSR, the [Angular SSR Guide](/guide/ssr) provides additional information regarding the setup process for adding SSR to an application.
+
+For applications that are already using SSR, additional manual adjustments will be needed to update the application SSR server to support the new integrated SSR capabilities.
+In the future, a schematic will make this migration process easier for existing applications.
 The `application` builder now provides the integrated functionality for all of the following preexisting builders:
 
 * `app-shell`
 * `prerender`
 * `server`
 * `ssr-dev-server`
 
-The [Angular SSR Guide](/guide/ssr) provides additional information regarding the new setup process for SSR.
+The `ng update` process will automatically remove usages of the `@nguniversal` scope packages where some of these builders were previously located.
+The new `@angular/ssr` package will also be automatically added and used with configuration and code being adjusted during the update.
+To convert from the separate SSR builders to the integrated capabilities of the `application` builder, there are several required manual steps.
+However, as each application is different, there may be more application specific changes needed beyond these to complete the process.
+
+1. Combine SSR builder options into the `application` builder options in the `angular.json` file.
+2. Combine server TypeScript configuration from `tsconfig.server.json` into `tsconfig.app.json`.
+3. Remove and/or update any `npm` scripts referencing the old builder targets.
+4. Update application server code to remove Webpack specific elements.
+5. Remove any CommonJS assumptions in the application server code.
+
+To provide an example of the specific changes needed to convert an existing v16 project, a repository with individual commits outlining the steps is available:
+INSERT LINK HERE
+In the future, a schematic will make this migration process easier for existing applications.
 
 ## Executing a build