Adding Cosign to the list of Container Signing (#3)

Cosign is a beautiful project under sigstore. It is being used for signing the images and is compatible with almost all the OCI Registries.

README.md

@@ -169,6 +169,7 @@ Dynamic application security testing (DAST) is a type of application testing (in
 | **Falco** | [https://github.com/falcosecurity/falco](https://github.com/falcosecurity/falco) | Container runtime protection |![Falco](https://img.shields.io/github/stars/falcosecurity/falco?style=for-the-badge) | 
 | **Trivy** | [https://github.com/aquasecurity/trivy](https://github.com/aquasecurity/trivy) | Comprehensive scanner for vulnerabilities in container images |![Trivy](https://img.shields.io/github/stars/aquasecurity/trivy?style=for-the-badge) | 
 | **Notary** | [https://github.com/notaryproject/notary](https://github.com/notaryproject/notary) | Docker signing|![Notary](https://img.shields.io/github/stars/notaryproject/notary?style=for-the-badge) | 
+| **Cosign** | [https://github.com/sigstore/cosign](https://github.com/sigstore/cosign) | Container signing|![Cosign](https://img.shields.io/github/stars/sigstore/cosign?style=for-the-badge) | 
 | **watchtower** | [https://github.com/containrrr/watchtower](https://github.com/containrrr/watchtower) | Updates the running version of your containerized app |![watchtower](https://img.shields.io/github/stars/containrrr/watchtower?style=for-the-badge) |