Merge branch 'en/rename-limits-doc'

Documentation on "git diff -l<n>" and diff.renameLimit have been
updated, and the defaults for these limits have been raised.

* en/rename-limits-doc:
  rename: bump limit defaults yet again
  diffcore-rename: treat a rename_limit of 0 as unlimited
  doc: clarify documentation for rename/copy limits
  diff: correct warning message when renameLimit exceeded

diff --cc diff.c
Simple merge

diff --cc diffcore-rename.c
Simple merge

diff --cc merge-ort.c
Simple merge

diff --cc merge-recursive.c
Simple merge