Remove docs reference to discussions (#1297)

## Description

Now disabled on Github

## Type of change

- [x] 🗺️ Documentation

docs/docusaurus.config.js

@@ -104,10 +104,6 @@ const config = {
           {
             title: 'Community',
             items: [
-              {
-                label: 'Discussions',
-                href: 'https://github.com/alcionai/corso/discussions',
-              },
               {
                 label: 'Discord',
                 href: 'https://discord.gg/63DTTSnuhT',