Eclipse and Doxygen can be a bit non-obvious to configure. Once again StackOverflow allows people who know absolutely nothing to close questions. I have written about the closed question more than once on here. Give people without a clue a little bit of power and they will run amuck.
Eclipse is not something I use often. There are a few embedded systems shops still using it but most roll their own cross compile or use the general one provided by the SOM vendors. Usually they are too busy to give you either a config file or written instructions on how to configure Eclipse for their shop. Almost every project uses Doxygen these days. One of the most active questions on StackOverflow is that closed question which should tell you what a trash heap “the stacks” have become.
Words Don’t Explain It
Almost everybody types Window->Preferences->Editor and kind of stops there.
That combobox in the “Documentation tool comments” frame. Change it to Doxygen.
If you do not see Doxygen as an option, exit eclipse, use the Synaptic package manager to install doxygen and graphviz. Restart your computer just in case, then start Eclipse and try again.