Update README.md

Author: remcoder

README.md

@@ -38,6 +38,9 @@ Click to see the interactive demo:
   preview.processGCode(gcode);
 ```
 
+### API Docs
+Check the full API documentation at https://gcode-preview.web.app/doc
+
 ### Vue.js / React / Svelte integration
 <img src="https://vuejs.org/logo.svg" height="40px" />