refactor: remove 'Getting Started' section from iApp sidebar and delete corresponding guide

Author: Le-Caignec

.vitepress/sidebar.ts

@@ -192,10 +192,6 @@ export function getSidebar() {
             text: 'Introduction',
             link: '/guides/use-iapp/introduction',
           },
-          {
-            text: 'Getting Started',
-            link: '/guides/use-iapp/getting-started',
-          },
           {
             text: 'How to Pay the Executions',
             link: '/guides/use-iapp/how-to-pay-executions',