fix(vpc): add faq question

Author: RoRoJ

pages/vpc/faq.mdx

@@ -83,6 +83,10 @@ You can configure:
 - Up to 255 Private Networks per Organization
 - Up to 512 Scaleway resources per Private Network
 
+### Does a resource's advertised bandwidth limit apply to public connections only, or also to Private Networks?
+
+This limit applies per network connection. For example, an Instance offer with a bandwidth of `500 Mbps`, gets 500 Mbps to the internet, and 500 Mbps to each Private Network.
+
 ## Compatibility and integration
 
 ### Are Serverless Functions and Containers compatible with VPC routing?