Add documentation for sandbox resources to Sphinx docs.
Add documentation for sandbox resources to Sphinx docs.

vishwaprakashmishra/xmatrix,harrissoerja/vumi,harrissoerja/vumi,TouK/vumi,vishwaprakashmishra/xmatrix,TouK/vumi,harrissoerja/vumi,vishwaprakashmishra/xmatrix,TouK/vumi