Clarify the grant-free schema 2 contract

wit/filesystem.wit

@@ -36,9 +36,10 @@ interface host {
         pull: func(limit: u32) -> result<list<u8>, host-error>;
     }
     /// Begins a request to any HTTP or HTTPS host, including LAN and loopback
-    /// addresses. Each redirect and DNS result is checked, and DNS is pinned.
-    /// Cross-origin redirects remove request headers; HTTPS cannot downgrade.
-    /// The host bounds total bytes per exchange, not buffer size.
+    /// addresses. This API has no per-connection network grant. Each redirect
+    /// and DNS result is checked, and DNS is pinned. Cross-origin redirects
+    /// remove request headers; HTTPS cannot downgrade. The host bounds total
+    /// bytes per exchange, not buffer size.
     http: func(request: request) -> result<exchange, host-error>;
 
     /// One open TCP connection. Dropping the handle closes the socket, and the
@@ -51,9 +52,9 @@ interface host {
         write: func(data: list<u8>) -> result<u32, host-error>;
     }
     /// Opens a socket to any host, including LAN and loopback addresses, on a
-    /// package-declared port. The host resolves and pins DNS and starts TLS
-    /// when asked. Ports negotiated at runtime, such as an FTP data channel,
-    /// must be declared.
+    /// package-declared port. This API has no per-connection network grant.
+    /// The host resolves and pins DNS and starts TLS when asked. Ports
+    /// negotiated at runtime, such as an FTP data channel, must be declared.
     connect: func(host: string, port: u16, tls: bool) -> result<tcp, host-error>;
 
     /// One datagram socket connected to a single peer.
@@ -64,8 +65,8 @@ interface host {
         /// means none arrived inside the host's wait, not that the peer left.
         receive: func(limit: u32) -> result<list<u8>, host-error>;
     }
-    /// Connects a datagram socket under the same port rules as `connect`, for
-    /// the few filesystem protocols that still need one.
+    /// Connects a datagram socket under the same address and port rules as
+    /// `connect`, for the few filesystem protocols that still need one.
     bind: func(host: string, port: u16) -> result<udp, host-error>;
 
     /// A configuration value, typed as the package's manifest declared it.