Note that document link auto-includes instructions for tooltip

For https://github.com/microsoft/vscode/issues/74311#issuecomment-497127291

src/vs/vscode.proposed.d.ts

@@ -1442,6 +1442,10 @@ declare module 'vscode' {
 	interface DocumentLink {
 		/**
 		 * The tooltip text when you hover over this link.
+		 *
+		 * If a tooltip is provided, is will be displayed in a string that includes instructions on how to
+		 * trigger the link, such as `cmd + click to {0}`. The specific instructions vary depending on OS,
+		 * user settings, and localization.
 		 */
 		tooltip?: string;
 	}