docs: add B2B Suite only callout to README

Author: PedroAntunesCosta

docs/README.md

@@ -16,6 +16,8 @@ The B2B shopping experience frequently requires the possibility for customers to
 
 The **B2B Quotes & Carts** app allows customers who are part of [B2B Organizations](https://developers.vtex.com/vtex-developer-docs/docs/vtex-b2b-organizations) to request a quote for a shopping cart and save it for future use – including its items, product quantities and prices. This enables price negotiations between them and the store’s sales representatives, as well as order approval flows within their organization.
 
+> ⚠️ This specification applies to B2B Suite only.
+
 ## Before you start
 
 First, make sure you have the [VTEX IO CLI (Command Line Interface)](https://developers.vtex.com/vtex-developer-docs/docs/vtex-io-documentation-vtex-io-cli-install) installed in your machine.