ittywiki is a small, flat-file wiki.
it's written in php, so all your edits go live as soon as you upload them; there's no need to run a script to recompile your wiki just to fix a nasty typo.
every page is written in Markdown, with additional wiki features like linking, page summaries, and tooltips to make writing pages a breeze.
copy the entire ittywiki directory onto your server and go there. you should see the default wiki contents loaded.
replace the core folder with the new core. leave your wiki files untouched.