chore: add docs build and deploy badges

Author: bandantonio

README.md

@@ -1,3 +1,5 @@
 # showdownjs.github.io
 
+[![documentation](https://github.com/showdownjs/showdownjs.github.io/actions/workflows/docs.yml/badge.svg)](https://github.com/showdownjs/showdownjs.github.io/actions/workflows/docs.yml) [![pages-build-deployment](https://github.com/showdownjs/showdownjs.github.io/actions/workflows/pages/pages-build-deployment/badge.svg)](https://github.com/showdownjs/showdownjs.github.io/actions/workflows/pages/pages-build-deployment)
+
 [Showdown website](https://showdownjs.com/) and [documentation](https://showdownjs.com/docs/)