mklost+found: add page

[CleanMachine1]

• The page (if new), does not already exist in the repo.
• The page is in the correct platform directory (common/, linux/, etc.)
• The page has 8 or fewer examples.
• The PR title conforms to the recommended templates.
• The page follows the content guidelines.
• The page description includes a link to documentation or a homepage (if applicable)

Never seen or used the command, and it maybe could be an arch exclusive since I have never seen it on Debian based.

Unaware on how useful it really is since fsck will make one every boot anyway

[CleanMachine1]

Fun fact this is the 2nd page ever to have a + in the name