Add Revit schedule example with OpenRFA shared parameters implemented

[vdubya]

Start with the simplest example of a Revit schedule which implements OpenRFA shared parameters. Use as proof of concept to work out:

• where/how to present on website
• how/if to store on github
• one file per schedule versus one file for collection of related schedules
• Revit versions? Last 3? 2019, 2018, 2017?
• consensus building process (one approach would be a call for submission of examples used in practice, with an emphasis on real use cases instead of idealized versions); compare against NCS standard schedules
• template for schedule container file (remove all families, purge repeatedly until empty to minimize cruft and file size)
• whether or not to "unit test" with a family loaded with shared parameters to show the schedule in action
• user documentation on how to use