Merge branch 'kn/ref-migrate-skip-reflog'

"git refs migrate" can optionally be told not to migrate the reflog.

* kn/ref-migrate-skip-reflog:
  builtin/refs: add '--no-reflog' flag to drop reflogs

diff --cc Documentation/git-refs.adoc
Simple merge

diff --cc refs.c
Simple merge

diff --cc refs.h
Simple merge