docs: add some badges

README.md

+[![Last release](https://gitlab.adullact.net/adullact/pki/vagrant-puppet-cfssl/-/badges/release.svg)](https://gitlab.adullact.net/adullact/pki/vagrant-puppet-cfssl/-/releases)
+[![Pipelines](https://gitlab.adullact.net/adullact/pki/vagrant-puppet-cfssl/badges/main/pipeline.svg)](https://gitlab.adullact.net/adullact/pki/vagrant-puppet-cfssl/pipelines?ref=main)
+[![License : AGPL v3](https://img.shields.io/badge/License-AGPL3-blue.svg)](LICENSE.txt)
+[![Code of Conduct](https://img.shields.io/badge/Contributor-Code%20of%20conduct-blueviolet.svg?style=flat-square)](CODE_OF_CONDUCT.md)
+[![Contributing Welcome](https://img.shields.io/badge/Contributing-Welcome-fc7700.svg?style=flat-square)](CONTRIBUTING.md)
+
 # Vagrant CFSSL
 
 [[_TOC_]]