docs(CHANGES): note gp-sphinx v0.0.1a8 bump

Author: tony

CHANGES

@@ -36,6 +36,7 @@ _Notes on upcoming releases will be added here_
 ### Documentation
 
 - Visual improvements to API docs from [gp-sphinx](https://gp-sphinx.git-pull.com)-based Sphinx packages (#53)
+- Bump gp-sphinx docs stack to v0.0.1a8 (#54)
 
 
 ### CLI