  Computes the description to display for a property, given:

    * `required`: boolean indicating whether this property is required.

    * `property`: dictionary describing the property's data, with these fields:

      * `description`: string describing the property

      * `enum`: optional array indicating the accepted values for the property

      * `x-addedInMatrixVersion`: optional string indicating in which Matrix
        spec version this property was added.

      * `x-changedInMatrixVersion`: o