Add calendar cron command on self-hosting-var.mdx (#6009)

To enable Google Calendar integration, you need to run `yarn
command:prod cron:calendar:google-calendar-sync` in the worker
container. However, currently, the self-hosting guide does not tell you
how to do it. If you just follow the guide, only Gmail integration will
be enabled. So I added the command for calendar sync cron on
self-hosting-var.mdx.

packages/twenty-website/src/content/developers/self-hosting/self-hosting-var.mdx

@@ -13,6 +13,7 @@ Twenty offers integrations with Gmail and Google Calendar. To enable these featu
 # from your worker container
 yarn command:prod cron:messaging:messages-import
 yarn command:prod cron:messaging:message-list-fetch
+yarn command:prod cron:calendar:google-calendar-sync
 ```
 
 # Setup Environment Variables
@@ -208,4 +209,4 @@ yarn command:prod cron:messaging:message-list-fetch
     ['CAPTCHA_SECRET_KEY', '', 'The captcha secret key'],
 ]}></ArticleTable>
 
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+<ArticleEditContent></ArticleEditContent>