Adds some instructions to the API

apps/reference/_api/intro.md

@@ -4,6 +4,28 @@ sidebar_position: 1
 sidebar_label: Supabase API
 ---
 
-# Supabase API
+# Supabase API (Beta)
 
-Some docs
+The Supabase API allows you to manage your projects programmatically.
+
+## Status
+
+The API is currently in beta. It may have breaking changes.
+
+## Authentication
+
+All API requests require an `Authorization Bearer token`. 
+To generate or manage your API key, visit your [account](https://app.supabase.com/account/tokens) page. 
+Your API key carries the same privileges as your user account, so be sure to keep it secret.
+
+```bash
+$ curl https://api.supabase.com/v1/projects \
+-H "Authorization: Bearer sbp_bdd0••••••••••••••••••••••••••••••••4f23"
+```
+
+All API requests must be authenticated and made over HTTPS. 
+
+## Rate limits
+
+The API is currently subject to our fair-use policy. In the future, are likely to introduce rate limits.
+All resources created via the API are subject to the pricing detailed on our [Pricing](https://supabase.com/pricing) pages.