Fix broken RTD documentation builds

Patch raised here, need somebody to merge: https://github.com/AcademySoftwareFoundation/xstudio/pull/101

Here is the broken job, managed under the Linux Foundation readthedocs account:

Review pull request #101 and the broken Read the Docs job managed under the Linux Foundation account. Confirm that the patch addresses the documented build failure; the work is done when the RTD documentation build succeeds and the patch can be merged.

Written by the indexing model from the issue text.