QDoc is the name of a program that generates HTML, and a file format for documenting classes in C++ or QML, and also a filename extension for structured documentation. qdoc is like javadoc for Qt code, and also like a simplified LaTeX, supporting hierarchical sections, cross-document links, macros and such.
This plugin provides SideKick with hierarchical structure data on the currently editing .qdoc file. The elements QDocSideKick cares about are: \page \section1 \section2 \section3 \section4. This makes a decent tree to assist in navigating a qdoc file.