edit vercel marketplace docs on user account creation (#15087)

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Author: cobyeastwood183

docs/organization/integrations/deployment/vercel/index.mdx

@@ -97,6 +97,10 @@ Subscription settings can only be modified within Sentry. During setup, organiza
 
 ### User Access
 
+<Alert>
+  Only the individual who sets up Sentry using the one-click workflow will have a Sentry user account created for them. To enable single sign-on access from Vercel for other users, they must be invited to the Sentry organization.
+</Alert>
+
 Vercel users will have single sign-on access to Sentry using the "Open in Sentry" button within Vercel, and will be able to create new projects in either Vercel or Sentry. 
 
 Users will still be able to login to their Sentry organization directly, without using the Vercel single-sign on, by using the login they configured during the setup process. For non social based login (Google, Github, etc.) users, Sentry will prompt for password creation.