chore: Update v3.15 release notes with performance improvements and bug fixes

Author: hannesrudolph

docs/update-notes/v3.15.md

@@ -22,6 +22,9 @@ This release introduces prompt caching for Google Vertex, improved terminal comm
 *   Adjusted chat view padding to accommodate small width layouts (thanks @zhangtony239).
 *   Simplified and streamlined Roo Code's quick actions.
 *   Improved the auto-approve toggle buttons for some high-contrast VSCode themes.
+*   Offloaded expensive count token operations to a web worker for better performance (thanks @samhvw8).
+*   Improved support for multi-root workspaces (thanks @snoyiatk).
+*   Improved the performance of mode switching (thanks @dlab-anton).
 
 ## Bug Fixes
 
@@ -35,8 +38,4 @@ This release introduces prompt caching for Google Vertex, improved terminal comm
 
 ## Misc Improvements
 
-*   Added a reasoning effort setting for the OpenAI Compatible provider (thanks @mr-ryan-james).
-*   Offloaded expensive count token operations to a web worker for better performance (thanks @samhvw8).
-*   Improved support for multi-root workspaces (thanks @snoyiatk).
-*   Removed unused types (thanks @wkordalski).
-*   Improved the performance of mode switching (thanks @dlab-anton).
+*   Removed unused types (thanks @wkordalski).