RelNotes: spelling & grammar fixes

Signed-off-by: Marc Branchaud <marcnarc@xiplink.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Merge branch 'mb/relnotes-1.8.5-fix'

* mb/relnotes-1.8.5-fix:
  RelNotes: spelling & grammar fixes
Git 1.8.4.4

Signed-off-by: Junio C Hamano <gitster@pobox.com>
Sync with 1.8.4.4
Git 1.8.5-rc3

Signed-off-by: Junio C Hamano <gitster@pobox.com>