Doc of vc-next-action

[Chong Yidong]

I'd like to get a second opinion on the docstring of vc-next-action:

   If every file is not already registered, this registers each one for version
     control.  This does an add, but not a commit.
   If every file is added but not committed, each one is committed.
   If every working file is changed, but the corresponding repository file is
     unchanged, this pops up a buffer for entry of a log message; when the
     message has been entered, it checks in the resulting changes along
     with the logmessage as change commentary.  A writable file is retained.
   If the repository file is changed, you are asked if you want to
     merge in the changes into your working copy.

The descriptions in No. 3 and 4 look like CVS-isms.  Regarding No. 3, on
distributed VCSes we don't check that "the corresponding repository file
is unchanged", as that's not a meaningful condition.  And No. 4 seems to
refer to the `needs-update' value of vc-state, which isn't used on
distributed VCSes.  Correct?