Yitro - meaning "his addition."
"In this, the case of Jethro is unique. In all other instances, nothing was added to the Torah--these were laws that would have been included in the Torah in any case, for without them the Torah is not complete; it was only that instead of being communicated directly to Moses as was the rest of the Torah, certain individuals had the merit to be involved in the process of their revelation. Only Jethro's section is referred to as an addition--something that would not have been part of the Torah were it not for his initiative. In other words, the Torah was complete without this section, and Jethro added something to it."
Jethor's addition was his advice to Moses to delegate the judical authority. Moses would continue to teach the people but the resolution of disputes in the daily life of the Israelites should be settled by minor judges. Moses would still decide the most difficult issues. Note that Jethro's suggestions was that Moses would still decide the most important issues. Moses' revision to the most difficult makes him avaiaalble to all classes and types of persons.