Rework /doc/advanced_topics/virtualization/

- Simplify text

- Simplify the subpages to fit on a single page

- Fix the information about running Tails from Windows

- Fix markup

- List more virtualization solutions

- Mention VirtualBox limitations and bugs
- Mention libvirt

Feature Branch: doc/7143-virtualization

Original created by @sajolida on 7143 (Redmine)

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information