refactor(@schematics/angular): improve optional application migration description

The description for the optional application builder migration has been adjusted
to include an update adev link as well as a shorter first sentence which is used
as the content for the optional migration selection prompt.

Author: clydin

packages/schematics/angular/migrations/migration-collection.json

@@ -3,7 +3,7 @@
     "use-application-builder": {
       "version": "18.0.0",
       "factory": "./use-application-builder/migration",
-      "description": "Migrate application projects using the '@angular-devkit/build-angular' package's 'browser' and/or 'browser-esbuild' builders to the 'application' builder. Read more about this here: https://angular.dev/tools/cli/esbuild#using-the-application-builder",
+      "description": "Migrate application projects to the new build system. Application projects that are using the '@angular-devkit/build-angular' package's 'browser' and/or 'browser-esbuild' builders will be migrated to use the new 'application' builder. You can read more about this, including known issues and limitations, here: https://angular.dev/tools/cli/build-system-migration",
       "optional": true
     }
   }