Update first-web-api.md (dotnet#12935)

Author: guardrex

aspnetcore/tutorials/first-web-api.md

@@ -4,7 +4,7 @@ author: rick-anderson
 description: Learn how to build a web API with ASP.NET Core.
 ms.author: riande
 ms.custom: mvc
-ms.date: 02/4/2019
+ms.date: 06/18/2019
 uid: tutorials/first-web-api
 ---
 
@@ -271,7 +271,7 @@ The return type of the `GetTodoItems` and `GetTodoItem` methods is [ActionResult
 
 This tutorial uses Postman to test the web API.
 
-* Install [Postman](https://www.getpostman.com/apps)
+* Install [Postman](https://www.getpostman.com/downloads/)
 * Start the web app.
 * Start Postman.
 * Disable **SSL certificate verification**