add minimal rosdoc files

mainpage.dox

+/**
+\mainpage
+
+\htmlinclude manifest.html
+
+<!--
+Provide an overview of your package.
+-->
+
+
+*/

rosdoc.yaml

+ - builder: doxygen
+   name: C++ API
+   output_dir: panda_teaching
+   file_patterns: '*.c *.cpp *.h *.cc *.hh *.dox'
+   homepage: https://st.inf.tu-dresden.de/ceti-robots