docs: update status badge

Author: lars-reimann

README.md

@@ -1,6 +1,6 @@
 <img src="img/logo_with_text.svg" alt="logo" height="75">
 
-[![Master](https://github.com/lars-reimann/api-editor/actions/workflows/master.yml/badge.svg?branch=master)](https://github.com/lars-reimann/api-editor/actions/workflows/master.yml)
+[![Main](https://github.com/lars-reimann/api-editor/actions/workflows/main.yml/badge.svg)](https://github.com/lars-reimann/api-editor/actions/workflows/main.yml)
 
 ## For users