You can use these areas to write down additional notes concerning your Docklight application. E.g., how to use the Send / Receive Sequences and sequence parameters, or notes on additional test equipment, etc.
The documentation contents are stored and loaded along with all other Docklight project settings (see saving and loading your project data, scripts, and options).
TIP: The documentation areas are simple text boxes without formatting menus or tools. For formatted documentation including pictures and tables, you can prepare your documentation in Windows WordPad or Microsoft Word and use copy&paste to add it to the Docklight documentation area.