Describe onDidChangeShell data

Fixes microsoft#194229

Author: Tyriar

src/vscode-dts/vscode.d.ts

@@ -10072,7 +10072,8 @@ declare module 'vscode' {
 		export const onDidChangeTelemetryEnabled: Event<boolean>;
 
 		/**
-		 * An {@link Event} which fires when the default shell changes.
+		 * An {@link Event} which fires when the default shell changes. This fires with the new
+		 * shell path.
 		 */
 		export const onDidChangeShell: Event<string>;