docs: add OpenSSF Baseline badge (#181)

Author: mshick

README.md

@@ -8,6 +8,7 @@
 [![Check dist/](https://github.com/mshick/add-pr-comment/actions/workflows/check-dist.yml/badge.svg)](https://github.com/mshick/add-pr-comment/actions/workflows/check-dist.yml)
 [![CodeQL](https://github.com/mshick/add-pr-comment/actions/workflows/codeql.yml/badge.svg)](https://github.com/mshick/add-pr-comment/actions/workflows/codeql.yml)
 [![Coverage](./badges/coverage.svg)](./badges/coverage.svg)
+[![OpenSSF Baseline](https://www.bestpractices.dev/projects/12345/baseline)](https://www.bestpractices.dev/projects/12345)
 
 A GitHub Action which adds a comment to a pull request issue or commit.