update release notes

Author: rickwierenga

docs/release_notes.md

@@ -17,4 +17,6 @@
     [VTAB benchmark](https://arxiv.org/abs/1910.04867).
 *   Add e-SNLI dataset from the paper
     [e-SNLI](http://papers.nips.cc/paper/8163-e-snli-natural-language-inference-with-natural-language-explanations.pdf).
+*   Add SCAN dataset introduced
+    [here](https://arxiv.org/pdf/1711.00350.pdf).
 *   Add [Imagewang](https://github.com/fastai/imagenette) dataset.