bug#16687: 24.3.50; completion doc errors

[Leo Liu]

The doc disagrees with the function's doc-string:

,----[ (info "(elisp)Completion Variables") ]
|      The TRY-COMPLETION and ALL-COMPLETIONS functions should each
|      accept four arguments: STRING, COLLECTION, PREDICATE, and POINT.
|      The STRING, COLLECTION, and PREDICATE arguments have the same
|      meanings as in `try-completion' (*note Basic Completion::), and
|      the POINT argument is the position of point within STRING.  Each
|      function should return a non-`nil' value if it performed its job,
|      and `nil' if it did not (e.g., if there is no way to complete
|      STRING according to the completion style).
`----

It seems this should be `five' instead of `four':

,----[ (info "(elisp)Programmed Completion") ]
|    * A flag specifying the type of completion operation to perform.
|      This is one of the following four values:
`----

Leo