See
http://download.dokuwiki.org/
There is an 'Update' option which is described there and would be useful if you've been successively updating after each hotfix warning, but the other option is to do a complete upgrade, which would include any previous hotfixes. In the latter case you can use the
upgrade plugin. Generally Dokuwiki is designed to accept upgrades without problems. But you should backup, especially so if you have done any altering of the installed distribution (see:
install:upgrade). In my own case, for instance, I often personalize the Dokuwiki template and without a backup I would lose the changes that I've made.