edit release notes to reflect new constructor taking list of vertices.
### Version 0.0.20 ###
## Common
-* Can save dot files with disconnected vertices in BayesianNetwork.
+* Can save dot files with disconnected vertices in BayesianNetwork. You can also just pass a list of vertices to DotSaver.
* Plates have been renamed
* This was done primarily because we were using the term incorrectly, since Dynamic Bayes Nets (e.g. Hidden Markov) are not Plates.
* `Plates` --> `Sequence`
