Fix JSDoc grammatical error (microsoft#184090)

Author: joyceerhl

src/vscode-dts/vscode.d.ts

@@ -16362,7 +16362,7 @@ declare module 'vscode' {
 		appendOutput(output: string, location?: Location, test?: TestItem): void;
 
 		/**
-		 * Signals that the end of the test run. Any tests included in the run whose
+		 * Signals the end of the test run. Any tests included in the run whose
 		 * states have not been updated will have their state reset.
 		 */
 		end(): void;