add configuration docs link to missing configs error msg (#856)

Author: jordanstephens

src/pkg/cli/compose/validation.go

@@ -25,7 +25,7 @@ type ListConfigNamesFunc func(context.Context) ([]string, error)
 type ErrMissingConfig []string
 
 func (e ErrMissingConfig) Error() string {
-	return fmt.Sprintf("missing configs %q", ([]string)(e))
+	return fmt.Sprintf("missing configs %q (https://docs.defang.io/docs/concepts/configuration)", ([]string)(e))
 }
 
 var ErrDockerfileNotFound = errors.New("dockerfile not found")

src/tests/interpolate/compose.yaml.warnings

@@ -1,4 +1,4 @@
  ! Environment variable "NODE_ENV" is not used; add it to `.env` if needed
  ! Environment variable "NODE_ENV" is not used; add it to `.env` or it may be resolved from config during deployment
  ! service "interpolate": missing memory reservation; using provider-specific defaults. Specify deploy.resources.reservations.memory to avoid out-of-memory errors
-missing configs ["NODE_ENV" "POSTGRES_PASSWORD" "def"]
+missing configs ["NODE_ENV" "POSTGRES_PASSWORD" "def"] (https://docs.defang.io/docs/concepts/configuration)