Add fallback and shortcut to good-old dd instructions

Add shortcut from Debian and expert to Linux to prevent installing extra stuff [36]
- Point people with Wheezy to dd
- Explain briefly dd as alternative to GNOME Disks [61]
- Add bug note about previous versions of GNOME Disks [61]

Feature Branch: web/10642-fallback-to-dd

Original created by @sajolida on 10642 (Redmine)

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