docs: explicitly enable seeding on remote (supabase#39309)

Author: sweatybridge

apps/docs/content/guides/deployment/branching/configuration.mdx

@@ -24,6 +24,7 @@ Here's an example of configuring a separate seed script for a staging environmen
 project_id = "your-project-ref"
 
 [remotes.staging.db.seed]
+enabled = true
 sql_paths = ["./seeds/staging.sql"]
 ```