Fix links in installation.md to point to existing files in dev (#5174)
Fix links in installation.md to point to existing files in dev (#5174)

Cleaned up and corrected https://github.com/DefectDojo/django-DefectDojo/pull/5158 to now point to dev in order to fix https://defectdojo.github.io/django-DefectDojo/getting_started/installation/
rackerlabs/django-DefectDojo,rackerlabs/django-DefectDojo,rackerlabs/django-DefectDojo,rackerlabs/django-DefectDojo