First of all, why would you want to make your own wiki ? This may seem like a bad, or just not-so-good, idea when you say it, but let me explain why you should consider it.
Either you are into computer science or not, a wiki feels like the best place to have a documentation about your passions, job or any other topic that you could share to others, or that needs a strict configuration process.
Even if you think that what you've done is only for yourself and would not interest anyone, others may be in a situation where they would have to, or like to, reproduce part of your work, and letting them know how to do so via a documentation written while you were fresh about a topic is way better than trying to remember each step correctly weeks, months or years after you've done them: in case you have a wiki page about it, you just can throw them the page link et voilà.
On top of this sharing knowledge advantage, and as mentioned, you will forget stuff as time passes, so to have solid bases, and because it's easier for you to search on your own wiki about a topic once it starts fading out of your mind, having a wiki will be an advantage to prevent time loss over tasks you've done before.
In addition to that need for strict directives, documenting your journey, your difficulties and how you solved them is a good way to acknowledge what you've done, been through and accomplished, either you want to acknowledge others, or yourself.
Of course you're thinking “then why not making a blog website” and to this we could answer that a blog website is good, on top of having a personal wiki, because sometimes what you want to share to others is just branding, so blog posts are fine, but if you want to share more knowledge, and let the community help about it, then you may want a wiki.
Of course the main advantage of a wiki over some local files is that you can build that knowledge base with a community, with everyone helping each other in order to assemble more precise information, or just more information at all, and this on basically any topic, because others may have pieces of information you don't have, and vice versa.