[MLton] user guide

[Stephen Weeks]

> While I don't strongly object to having the User Guide only on the
> wiki, slightly in favor of having the LaTeX/ps/pdf.

Having the text in two places causes too many problems with
synchronicity and maintaining both.

> In any case, what is the policy for maintaining the User Guide.  I
> guess we'll end up with UserGuide:CVS and UserGuide:Experimental
> pages to stockpile documentation that corresponds to features that
> aren't in the current release.

Another alternative that I have seen is to integrate the new
documentation directly on the pages, adding a note for new stuff that
says something like "this feature was added after release 20041109".
That way, the same documentation can be used by users of different
versions (admittedly with a little more care).  And we get to put the
documentation roughly where it belongs.  Also, stable users can always
look at the documentation snapshot that came with their release if
they want to see what it looked like at the time.