Tracking: Improving FDE content.

[flexibeast]

This issue consolidates #284, #375, #398 and #432. Further requests for corrections / improvements to FDE-related content should be made here, until all outstanding issues have been resolved.

• Refactor "Full Disk Encryption" section (Refactor FDE section #284)
• Add information regarding swap(/files) and hibernation in Full Disk Encryption (Add information regarding swap(/files) and hibernation in Full Disk Encryption  #375)
• FDE + EFI reworking (FDE + EFI installation chapter needs reworking? #398)
• Clarify what steps need to be taken to enable TRIM on an FDE setup (Request: Clarify what steps need to be taken to enable TRIM on an FDE setup #432)

i'll close #284, #375, #398 and #432 as superseded by this issue, but of course, the discussions in those issues should still be referred to.

cc: @Kratacoa, @brihadeesh, @cinerea0

[Kratacoa]

In case it may be useful, I have documented my personal installation in this gist, using BTRFS + swapfile encryption.
However, it is an incomplete guide (it is missing secure boot and proper SSD configuration).
I may contribute once I inquire again into it and have a clearer idea of what's going on.

[ghost]

I would like to see a guide added that does not encrypt /boot, but only encrypts /.