chore: added a link to the CI workflow (#509)

* Update README.md

* Update README.md

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Co-authored-by: Nico Flaig <nflaig@protonmail.com>
Co-authored-by: Paul Harris <paul.harris@consensys.net>

Author: 3 people

README.md

@@ -1,6 +1,6 @@
 # Ethereum Beacon APIs
 
-![CI](https://github.com/ethereum/beacon-APIs/workflows/CI/badge.svg)
+[![CI](https://github.com/ethereum/beacon-APIs/workflows/CI/badge.svg)](https://github.com/ethereum/beacon-APIs/actions/workflows/main.yml?query=branch%3Amaster)
 
 Collection of RESTful APIs provided by Ethereum Beacon nodes