Add build status

Author: PussInDasBoot

README.rst

@@ -62,6 +62,8 @@ License
 
 HiPerSeis is licensed under the GPL version 3
 
+.. |Build Status| image:: https://github.com/GeoscienceAustralia/hiperseis/actions/workflows/hiperseis_main_ci.yml/badge.svg
+   :target: https://github.com/GeoscienceAustralia/hiperseis/actions/workflows/hiperseis_main_ci.yml
 
 .. |Coverage Status| image:: https://codecov.io/gh/GeoscienceAustralia/hiperseis/branch/develop/graph/badge.svg
    :target: https://codecov.io/gh/GeoscienceAustralia/hiperseis