You can disable the forced capitalization with
$wgCapitalLinks = false;
Docs for this & links to some related settings are available on
Beware though that this will make the first letter of a title
case-sensitive in all page links and URLs: for instance '[[foo]]' will
no longer link to the page 'Foo', and '[[Foo]]' will not link to the
page 'foo', unless redirects are put in place. Migrating an existing
site can be tricky!
You can also use the 'DISPLAYTITLE' built-in parser function to adjust
the displayed title to initial lowercase without altering other
behavior on the site. There's a template on English Wikipedia which
conveniently wraps it, which you might copy (requires ParserFunctions
extension to be installed):
Thank you for good information, Brion.
I see some pros & cons for both options. I'll test them out in a test
wiki environment and make a decision.