Add badges to readme (open-telemetry#3773)

Author: thompson-tomo

README.md

@@ -7,6 +7,7 @@ Status](https://github.com/open-telemetry/opentelemetry-cpp/actions/workflows/ci
 [![Release](https://img.shields.io/github/v/release/open-telemetry/opentelemetry-cpp?include_prereleases&style=)](https://github.com/open-telemetry/opentelemetry-cpp/releases/)
 [![FOSSA License Status](https://app.fossa.com/api/projects/custom%2B162%2Fgithub.com%2Fopen-telemetry%2Fopentelemetry-cpp.svg?type=shield&issueType=license)](https://app.fossa.com/projects/custom%2B162%2Fgithub.com%2Fopen-telemetry%2Fopentelemetry-cpp?ref=badge_shield&issueType=license)
 [![FOSSA Security Status](https://app.fossa.com/api/projects/custom%2B162%2Fgithub.com%2Fopen-telemetry%2Fopentelemetry-cpp.svg?type=shield&issueType=security)](https://app.fossa.com/projects/custom%2B162%2Fgithub.com%2Fopen-telemetry%2Fopentelemetry-cpp?ref=badge_shield&issueType=security)
+[![OpenSSF Scorecard](https://api.scorecard.dev/projects/github.com/open-telemetry/opentelemetry-cpp/badge)](https://scorecard.dev/viewer/?uri=github.com/open-telemetry/opentelemetry-cpp)
 
 The C++ [OpenTelemetry](https://opentelemetry.io/) client.