by Alex Walker.
There's a renderer called block_navigation that's used to build the navigation tree, using $this->page->navigation. This is built by calling the global_navigation function.
I've never done this, so I've looked into it just out of interest. You can add links to the navigation structure apparently. If you're wanting to do this across the site in a neat way, you might want to see if this can be done at a theme level. For example, I'd see if I could integrate this code in my theme's layout files.
Hopefully, one of the big front-end customisers can help you out here. Personally, I disabled the Navigation block in our moodle and replaced it with two custom ones: 'My Courses' and 'Dashboard'.