That file is fine, just don't use the included eq2ui_mainhud.xml, it is outdated. Instead copy the one from your \UI\Default folder into your EQ2MAP folder and add this line
<include>eq2ui_mainhud_notes.xml</include>
You will need to do that everytime SOE updates that file.
Take note of his installation instructions otherwise, you need to run a batch file which will create the xml, and then move that xml into your eq2map folder.
Another mod that also has a notes section is Milquetowst InfoCenter btw.