Re: [PATCH v2] doc: mention that 'git submodule update' fetches missing commits

Philippe Blain [off-list ref] writes:

'git submodule update' will fetch new commits from the submodule remote
if the SHA-1 recorded in the superproject is not found. This was not
mentioned in the documentation.

Helped-by: Junio C Hamano [off-list ref]
Helped-by: Johannes Schindelin [off-list ref]
Signed-off-by: Philippe Blain <redacted>
Signed-off-by: Junio C Hamano <redacted>
---
Changes since v1 [4]:
- Added my signed-off, corrected my email address
  and shortened the title of the commit message
  (I had actually done that when I resent my patch in [1] using submitGit, 
  but this dit not add the "v2" prefix)
- Added Junio's suggestion [2] (which was applied in [3] on top of the original 
  submission [4] instead of the revised one [1]), and squashed
- Added Helped-by trailers
- Rebased on v2.23.0 (as was done for [3])

Thanks, will replace.  This should be ready for 'next', I would
think.