Update RELEASE_NOTES.md

Author: DanielGoldfarb

RELEASE_NOTES.md

@@ -4,7 +4,7 @@
 ### <a name="v0.12.7a12"></a>v0.12.7a12 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; released 2021-04-09
 
 - <a name="v0.12.7a12"></a>v0.12.7a12 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; merged 2021-04-08
-  - Fixed kwarg **`return_calculated_values**
+  - Fixed kwarg **`return_calculated_values`**
     - It was *not* returning all values for `type='pnf'` (point and figure).
     - See **[stackoverflow 66991998](https://stackoverflow.com/questions/66991998/)** for more information.
 - <a name="v0.12.7a11"></a>v0.12.7a11 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; merged 2021-03-26