Instal Sphinx theme for readthedocs.org
Instal Sphinx theme for readthedocs.org

Fixing
```
Theme error:
sphinx_rtd_theme is no longer a hard dependency since version 1.4.0. Please install it manually.
```

Rombur/DataTransferKit,Rombur/DataTransferKit,dalg24/DataTransferKit,ORNL-CEES/DataTransferKit,dalg24/DataTransferKit,Rombur/DataTransferKit,dalg24/DataTransferKit,ORNL-CEES/DataTransferKit,ORNL-CEES/DataTransferKit,Rombur/DataTransferKit,dalg24/DataTransferKit,ORNL-CEES/DataTransferKit