Tweaked link to action

Co-Authored-By: Casper Welzel Andersen <43357585+CasperWA@users.noreply.github.com>

README.md

@@ -30,7 +30,7 @@ Contribution guidelines and tips can be found in [CONTRIBUTING.md](CONTRIBUTING.
 ## Links
 
 - [OPTiMaDe Specification](https://github.com/Materials-Consortia/OPTiMaDe/blob/develop/optimade.rst), the human-readable specification that this library is based on.
-- [optimade-validator-action](https://github.com/Materials-Consortia/optimade-validator-action), a GitHub action that can be used to validate implementations from a URL.
+- [optimade-validator-action](https://github.com/Materials-Consortia/optimade-validator-action), a GitHub action that can be used to validate implementations from a URL (using the validator from this repo).
 - [OpenAPI](https://github.com/OAI/OpenAPI-Specification), the machine-readable format used to specify the OPTiMaDe API in [`openapi.json`](openapi.json).
 - [Interactive documentation](https://petstore.swagger.io/?url=https://raw.githubusercontent.com/Materials-Consortia/optimade-python-tools/master/openapi.json) generated from [`openapi.json`](openapi.json) (see also [interactive JSON editor](https://editor.swagger.io/?url=https://raw.githubusercontent.com/Materials-Consortia/optimade-python-tools/master/openapi.json)).
 - [pydantic](https://pydantic-docs.helpmanual.io/), the library used for generating the OpenAPI schema from [Python models](optimade/models).