Merge pages about containers/singularity/virtual machines
Information about virtual environments like virtual machines and containers are scattered over several pages. Please merge them into a single page. Relevant pages might be:
- doc.zih.tu-dresden.de/docs/software/singularity_recipe_hints.md
- doc.zih.tu-dresden.de/docs/software/singularity_power9.md
- doc.zih.tu-dresden.de/docs/software/ngc_containers.md
- doc.zih.tu-dresden.de/docs/software/containers.md
- doc.zih.tu-dresden.de/docs/software/virtual_machines.md