Add Status Badges to `README` & GitHub Pages

[Chrimle]

Status Badges for CI, Artifact publishing and GitHub Pages deployment are added to the README and index.md in GitHub Pages.

Checklist

• [x] Closes #210
• [x] Documentation (README.md) has been updated
• [ ] ~Version number updated in pom.xml and licenseInfo.mustache~
• [ ] ~Project has been compiled with mvn clean install~
• [ ] ~Updated generated-sources-files have been committed~