Update utils.ts (#167)

Author: sjjj986

packages/@apphosting/adapter-angular/src/utils.ts

@@ -55,7 +55,9 @@ export async function checkStandaloneBuildConditions(cwd: string): Promise<void>
 
   const { builder } = workspaceProject.targets.get(target)!;
   if (builder !== REQUIRED_BUILDER) {
-    throw new Error("Only the Angular application builder is supported.");
+    throw new Error(
+      "Only the Angular application builder is supported. Please refer to https://angular.dev/tools/cli/esbuild#for-existing-applications guide to upgrade your builder to the Angular application builder. ",
+    );
   }
 }
 
@@ -64,7 +66,9 @@ export async function checkStandaloneBuildConditions(cwd: string): Promise<void>
  */
 export function checkMonorepoBuildConditions(builder: string): void {
   if (builder !== REQUIRED_BUILDER) {
-    throw new Error("Only the Angular application builder is supported.");
+    throw new Error(
+      "Only the Angular application builder is supported. Please refer to https://angular.dev/tools/cli/esbuild#for-existing-applications guide to upgrade your builder to the Angular application builder. ",
+    );
   }
 }