bug#16190: 23.4; M-x captialize-word works incorrectly

[Drew Adams]

> > That's how capitalize-word is supposed to work.  It's not a bug, but
> > intended behavior.
> 
> Then its doc string is incorrect:
> 
>    capitalize-word is an interactive built-in function in `C source code'.
> 
>    It is bound to M-c.
> 
>    (capitalize-word ARG)
> 
>    Capitalize the following word (or ARG words), moving over.
>    This gives the word(s) a first character in upper case
>    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>    and the rest lower case.
>    ^^^^^^^^^^^^^^^^^^^^^^^^
>    With negative argument, capitalize previous words but do not move.

The key here is the *word that starts at point*.  With point after the `n'
here: "another", the word that starts at point is "other".

It could help for the doc to explicitly emphasize this, as an extra tip.
That is, to point out that there is no scanning backward to find the
maximal word, i.e., to find a non word-constituent character.

But this should be treated as extra info, implied by a statement
(missing, it seems) that the word starts at point.  "The following word"
is too loose a description to make this clear.