Use proper capitalization for string

Windows is a product name in this case.

UI/data/locale/en-US.ini

@@ -216,7 +216,7 @@ Updater.NoUpdatesAvailable.Title="No updates available"
 Updater.NoUpdatesAvailable.Text="No updates are currently available"
 Updater.FailedToLaunch="Failed to launch updater"
 Updater.GameCaptureActive.Title="Game capture active"
-Updater.GameCaptureActive.Text="Game capture hook library is currently in use. Please close any games/programs being captured (or restart windows) and try again."
+Updater.GameCaptureActive.Text="Game capture hook library is currently in use. Please close any games/programs being captured (or restart Windows) and try again."
 
 # quick transitions
 QuickTransitions.SwapScenes="Swap Preview/Output Scenes After Transitioning"