I recently discovered a nice package called poporg that allows you to pop open a temporary org-mode window when you are editing code comments so you can write them using nice org-mode formatting. When you are done, you close the window and go back to your code with the newly edited comment. This is a bit antithetical to embedding source code in org-mode files to document the code that way, but in fact I find I do a bit of both and still like to have comments in my code, so I really appreciate being able to format them nicely.
You can install the package by adding the following to your emacs config file
(use-package poporg :bind (("C-c /" . poporg-dwim)))
With this, hitting C-c / in your source code in or near a comment will open the org-mode window and the same key combo will close it again.
Pragmatic Emacs 