An improved category structure for better organizing the tutorials

In an effort to make it easier to search for BrDR tutorials, the Task Force and ProMiles recently undertook the challenge of reorganizing the tutorials on the BrDR Technical Support Training webpage (https://aashtowarebrdr.org/bridge-rating-and-design/training/). The new multi-level category provides better organization for the 150+ currently available tutorials. Please be aware that, under certain circumstances, tutorials were placed under more than one category for a better search experience.