Add note to aware users for checking piped repositories config

Signed-off-by: khanhtc1202 <khanhtc1202@gmail.com>

docs/content/en/docs-dev/user-guide/managing-application/adding-an-application.md

@@ -11,6 +11,8 @@ It represents the service which you are going to deploy. With PipeCD, all applic
 
 Each application can be handled by one and only one `piped`. Currently, PipeCD is supporting 5 kinds of application: Kubernetes, Terraform, CloudRun, Lambda, ECS.
 
+> Note: Be sure your application manifests repository is listed in [Piped managing repositories configuration](../managing-piped/configuration-reference/#gitrepository:~:text=No-,repositories,-%5B%5DRepository).
+
 Before deploying an application, it must be registered to help PipeCD knows
 - where the application configuration is placed
 - which `piped` should handle it and which platform the application should be deployed to

docs/content/en/docs-v0.49.x/user-guide/managing-application/adding-an-application.md

@@ -11,6 +11,8 @@ It represents the service which you are going to deploy. With PipeCD, all applic
 
 Each application can be handled by one and only one `piped`. Currently, PipeCD is supporting 5 kinds of application: Kubernetes, Terraform, CloudRun, Lambda, ECS.
 
+> Note: Be sure your application manifests repository is listed in [Piped managing repositories configuration](../managing-piped/configuration-reference/#gitrepository:~:text=No-,repositories,-%5B%5DRepository).
+
 Before deploying an application, it must be registered to help PipeCD knows
 - where the application configuration is placed
 - which `piped` should handle it and which platform the application should be deployed to