Fix release notes for version 1.15.1b

Signed-off-by: mr. m <[email protected]>

Author: mr-cheffy

src/release-notes/stable.json

@@ -3002,7 +3002,8 @@
     "extra": "",
     "fixes": [
       "Fixed issues with the folder context menu not working on collapsed mode",
-      "Fixed tab becoming invisible on some occasions when collapsing active folders"
+      "Fixed tab becoming invisible on some occasions when collapsing active folders",
+      "Fixed pinned tabs / folders not initializing correctly on some occations"
     ],
     "features": ["Updated to Firefox 142.0.1"],
     "changed": ["Moved 'Unpack Folder' next to 'Delete Folder' in the folder context menu"],