add instructions for custom registry

cli/cmd/connect/registry.go

@@ -20,13 +20,15 @@ func Registry(
 	}
 
 	// query for helm repo name
-	repoURL, err := utils.PromptPlaintext(fmt.Sprintf(`Provide the image registry URL: `))
+	repoURL, err := utils.PromptPlaintext(fmt.Sprintf(`Provide the image registry URL (include the protocol). For example, https://my-custom-registry.getporter.dev.
+Image registry URL: `))
 
 	if err != nil {
 		return 0, err
 	}
 
-	username, err := utils.PromptPlaintext(fmt.Sprintf(`Username: `))
+	username, err := utils.PromptPlaintext(fmt.Sprintf(`Provide the username/password for authentication (press enter if no authenicaiton is required).
+Username: `))
 
 	if err != nil {
 		return 0, err