In commit d4b4791, four files were renamed by adding a file extension .md
The files are CONTRIBUTING, COPYING, HACKING and INSTALL
This commit fixes the pending tasks and especially the bug where HACKING.md is
wrongly listed as HACKING in debian/plinth.docs and cause build failure for the
Debian package of Plinth
Signed-off-by: Joseph Nuthalapati <njoseph@thoughtworks.com>
Signed-off-by: Sunil Mohan Adapa <sunil@medhas.org>
Reviewed-by: Sunil Mohan Adapa <sunil@medhas.org>
