Dokuwiki by default doesn't set outgoing links to nofollow, and especially if used as open Wiki, spammers are likely to use the site for their linkbuilding purpose, and the site's PageRank in the process.

Follow these these steps to disable this feature.

Use the following URL if the link is not available in your template.

http://www.yourwiki.com/doku.php?do=admin&page=config

You will need to log in if you're not already are.

Find the option in the Anti-Spam Settings→relnofollow section.

Tick on the checkbox next to the option, and click on the Save button at the end of the page.