docs: added Discord badge to landing page

Author: ErikBjare

index.pug

@@ -25,8 +25,10 @@ article.wrapper.mt-4
       // Badges and stuff
       a.mr-2(href='https://github.com/ActivityWatch/activitywatch')
         img(title='GitHub stars' src='https://img.shields.io/github/stars/ActivityWatch/activitywatch.svg?style=social&label=Star')
-      a(href='https://twitter.com/ActivityWatchIt')
+      a.mr-2(href='https://twitter.com/ActivityWatchIt')
         img(title='Twitter followers' src='https://img.shields.io/twitter/follow/ActivityWatchIt.svg?style=social&label=Follow')
+      a(href='https://discord.gg/vDskV9q')
+        img(title='Discord members' src='https://img.shields.io/discord/755040852727955476.svg?style=social&label=Chat&logo=discord')
 
 div.container
   div.row