It is not clear from your post what you are really trying to achieve, but if I see it right, running web server on your local machine to store study notes does not appear very advantageous.
If you just want to take notes locally, e.g. on your laptop, why don't you just use a text editor? If you want to add formatting, maybe a text processor (think: Word/LibreOffice Writer).
All of these have the advantage that they can run without the need to install and maintain additional software - but they come with the same disadvantage that your localhost DokuWiki installation would have: that is, that you need to take care of backups yourself.
A better approach would be to install DokuWiki on a hosted server (you can get cheap hosting basically everywhere these days) and just lock it down, so only you have access to it. Advantage: you can access it from multiple devices (mobile, laptop, PC) and your provider has to worry about backups and security, not you.
Having said this, I of course have a DokuWiki running on localhost - for development, not for note-taking - and that works, of course. Just make sure your web server is configured to only allow access from the local machine (especially if you take the computer into public networks, like at Uni or in a café), and unless you are noting down military-grade secrets there, you should be fine with that.
