Add UEFI/SecureBoot docs from Ubuntu wiki

[rkratky]

This adds content related to UEFI Secure Boot from the Ubuntu Wiki -- as a part of the effort to migrate docs from the wiki.

Notes:

• The new articles are marked as WIP and not official docs.
• While I have updated the content, added semantic mark-up, and reformatted it, more work is needed, including clean ups and removals of obsolete info; there are also sections that are marked as needing fixes.
• The .wokeignore file has been moved to the root of the repo temporarily because of an upstream bug: https://github.com/get-woke/woke/issues/212

[kukrimate]

@rkratky a large part of this content is incredibly out of date, and some parts of it suggest insecure practices, I am honestly not sure if we should be displaying this in this state anywhere.