Free text lines can be used to add descriptions for just about anything.
Note: Free Text Lines should be seldom used and cautious in their use. An equipment list full of free text lines is no more useful than a list of equipment written on a piece of paper.
This can be done by selecting the edit/hotkeys button and selecting Insert free text which will place the new Freetext line at the currently selected position in the list.
This creates a new Freetext line
You can now overwrite the line with the description you require