MAINTAINERS, nilfs2: change project home URLs

The domain of NILFS project home was changed to "nilfs.sourceforge.io"
to enable https access (the previous domain "nilfs.sourceforge.net" is
redirected to the new one).  Modify URLs of the project home to reflect
this change and to replace their protocol from http to https.

Link: http://lkml.kernel.org/r/1515416141-5614-1-git-send-email-konishi.ryusuke@lab.ntt.co.jp


Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>