mount.ddi: add page

[quantumflo]

• The page(s) are in the correct platform directories: common, linux, osx, windows, sunos, android, etc.
• The page(s) have at most 8 examples.
• The page description(s) have links to documentation or a homepage.
• The page(s) follow the content guidelines.
• The PR title conforms to the recommended templates.
• Version of the command being documented (if known):

[sebastiaanspeck]

mount.ddi will not work as command, but mount -t ddi will, maybe add this to the mount-page?

[acuteenvy]

This is not an alias.

INVOCATION AS /SBIN/MOUNT.DDI
The systemd-dissect executable may be symlinked to /sbin/mount.ddi. If invoked through that it implements
mount(8)'s "external helper" interface for the (pseudo) file system type "ddi". This means
conformant disk images may be mounted directly via

# mount -t ddi myimage.raw targetdir/

in a fashion mostly equivalent to:

# systemd-dissect --mount myimage.raw targetdir/

mount.ddi --mount myimage.raw targetdir/ doesn't work. The equivalent is mount.ddi myimage.raw targetdir/.

[kbdharun]

LGTM, after @acuteenvy's suggestion.

[quantumflo]

@kbdharun Please re add me as maintainer. I was removed due to 2 factor authentication not being enabled

[kbdharun]

@kbdharun Please re add me as maintainer. I was removed due to 2 factor authentication not being enabled

Done, I have sent an invitation.