Add more additional frontend information

README.md

@@ -2,7 +2,7 @@
 
 [GitLab](https://gitlab.tugraz.at/dbp/esign/dbp-relay-esign-bundle) |
 [Packagist](https://packagist.org/packages/dbp/relay-esign-bundle) |
-[ESign Application](https://gitlab.tugraz.at/dbp/esign/signature) |
+[Frontend Application](https://gitlab.tugraz.at/dbp/esign/signature) |
 [ESign Website](https://dbp-demo.tugraz.at/site/software/esign.html)
 
 The electronic signature bundle provides an API for interacting with multiple
@@ -11,6 +11,8 @@ servers and allows signing and signature verification of PDF files using [PAdES]
 
 For more details see the [docs](./docs/index.md) or the [ESign Website](https://dbp-demo.tugraz.at/site/software/esign.html).
 
+There is a corresponding frontend application that uses this API at [ESign Frontend Application](https://gitlab.tugraz.at/dbp/esign/signature).
+
 ## Bundle installation
 
 You can install the bundle directly from [packagist.org](https://packagist.org/packages/dbp/relay-esign-bundle).