Update README.md

Author: guilyx

README.md

@@ -1,6 +1,11 @@
 ![tests](https://github.com/APLA-Toolbox/pyjulia-pddl/workflows/tests/badge.svg?branch=main)
 ![build](https://github.com/APLA-Toolbox/pyjulia-pddl/workflows/build/badge.svg?branch=main)
 [![codecov](https://codecov.io/gh/APLA-Toolbox/pyjulia-pddl/branch/main/graph/badge.svg?token=63GHA9JUND)](https://codecov.io/gh/APLA-Toolbox/pyjulia-pddl)
+[![Maintenance](https://img.shields.io/badge/Maintained%3F-yes-green.svg)](https://GitHub.com/APLA-Toolbox/pyjulia-pddl/graphs/commit-activity)
+[![Percentage of issues still open](http://isitmaintained.com/badge/open/APLA-Toolbox/pyjulia-pddl.svg)](http://isitmaintained.com/project/APLA-Toolbox/pyjulia-pddl "Percentage of issues still open")
+[![GitHub license](https://img.shields.io/github/license/Apla-Toolbox/pyjulia-pddl.svg)](https://github.com/Apla-Toolbox/pyjulia-pddl/blob/master/LICENSE)
+[![GitHub contributors](https://img.shields.io/github/contributors/Apla-Toolbox/pyjulia-pddl.svg)](https://GitHub.com/Apla-Toolbox/pyjulia-pddl/graphs/contributors/)
+
 
 
 # Pyjulia PDDL