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

Author: tony

CHANGES

@@ -42,6 +42,7 @@ _Notes on the upcoming release will go here._
 ### Documentation
 
 - Visual improvements to API docs from [gp-sphinx](https://gp-sphinx.git-pull.com)-based Sphinx packages (#1035)
+- Bump gp-sphinx docs stack to v0.0.1a8 (#1036)
 
 
 ## tmuxp 1.67.0 (2026-03-08)