Legend Creator - Family Symbols tool in the Creators group of the Startup tool-set can help create legends for various family symbols. Let's create a Furniture Legend with the tool in this post.
The legend options and those legend columns look as follows in this example.
The content of the Furniture Legend may look as follows.
Detailed help can be got by following the path Project Setup => Creators => Legend Creator - Family Symbols on Revit Project Organizer.