Update README.md

Author: alexcheng1982

README.md

@@ -1,5 +1,7 @@
 # PDF Q&A
 
+[![build](https://github.com/JavaAIDev/pdf-qa/actions/workflows/build.yaml/badge.svg)](https://github.com/JavaAIDev/pdf-qa/actions/workflows/build.yaml)
+
 > See JavaAIDev [article](https://javaaidev.com/docs/rag/samples/pdf-qa) for more details.
 
 Q&A based on content of PDF files.