Add docs publishing CI workflow status badge to readme

Author: per1234

README.md

@@ -1,6 +1,7 @@
 # arduino-lint
 
 [![Tests Status](https://github.com/arduino/arduino-lint/workflows/Run%20tests/badge.svg)](https://github.com/arduino/arduino-lint/actions?workflow=Run+tests)
+[![Docs Status](https://github.com/arduino/arduino-lint/workflows/Publish%20documentation/badge.svg)](https://github.com/arduino/arduino-lint/actions?workflow=Publish+documentation)
 
 **arduino-lint** is a command line tool that checks for common problems in [Arduino](https://www.arduino.cc/) projects: