Bug 35713: Remove outdated debian/docs/LEEME.Debian file

Bug 35713: Remove outdated debian/docs/LEEME.Debian file

This removes the LEEME.Debian README file from the docs
directory. We don't even have an English README here as
we usually refer to the wiki for installation instructions.
It makes sense to remove it from the codebase.

To test:
* Verify that the file is removed
* Verify that all references to the file have been removed as well
  Example: git grep LEEME

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>
(cherry picked from commit a18e4d0e6241d4a18ceb62b7543c89cddd74bb1c)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>