The main goal of my blog was not to be interesting or show off (even though I do include my side projects etc.), but to write about specific issues I managed to solve. As a software developer, I'm googling for problems all the time. 95% of the time I land on StackOverflow or GitHub issues. But it's about those 5% that I find a blog post which really helps me. My goal was to contribute back the same way.
If you don't like to actively maintain a blog, just set up a GitHub repo + GitHub Pages (or even go for plain GitHub Gists). As long as the information can be found via a search engine, it's good enough.
Finally - don't create a blog just because you feel obliged to. It's totally fine as a developer not to have a blog.