bug#16106: 24.3.50; doc of `replace-match'

[Drew Adams]

> > State (in doc string and Elisp manual) that N in \N is not just "a
> > digit" but a digit from 1 through 9.  Make clear that in "Nth
> > subexpression", N is one-based, not zero-based.
> 
> I don't think that makes any sense.  The wording is:
> 
>   `\N' means substitute what matched the Nth `\(...\)'.
>        If Nth parens didn't match, substitute nothing.
> 
> I can't see anybody interpreting Nth as having "zeroth" as a valid
> meaning.

Most things in Emacs and Lisp in general are zero-based.
It is not obvious that this is one-based.  And Oth and zeroth
make as much sense as 1th and oneth.  If counting is zero-based
then the 0th element is exactly that: the entry that is indexed
by the number zero.