Replace link of pdvega repo
pdvega is no under altair-viz. The old link was not working anymore.
@@ -39,7 +39,7 @@ pdvega is a library that allows you to quickly create interactive Vega-Lite_ plo
.. List of links.
-.. _pdvega: https://github.com/jakevdp/pdvega
+.. _pdvega: https://github.com/altair-viz/pdvega
.. _Vega-Lite: https://vega.github.io/vega-lite/
.. _Jupyter: http://jupyter.org/
