RelNotes: spelling & grammar tweaks

Signed-off-by: Marc Branchaud <marcnarc@xiplink.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Git 2.2

Signed-off-by: Junio C Hamano <gitster@pobox.com>
Merge branch 'master' of https://github.com/ralfth/git-po-de

* 'master' of https://github.com/ralfth/git-po-de:
  l10n: de.po: fix typos