feat: incorporated improvements from NIP-11 discussion

Change descr to description.  Add `id` for websocket URL.  Use
integers for supported NIPs instead of strings.  Top-level is object,
instead of the array before.

config.toml

@@ -1,10 +1,15 @@
 # Nostr-rs-relay configuration
 
 [info]
+# The advertised URL for the Nostr websocket.
+relay_url = "wss://nostr.example.com/"
+
 # Relay information for clients.  Put your unique server name here.
 name = "nostr-rs-relay"
+
 # Description
 description = "A newly created nostr-rs-relay.\n\nCustomize this with your own info."
+
 # Administrative contact pubkey
 #pubkey = "0c2d168a4ae8ca58c9f1ab237b5df682599c6c7ab74307ea8b05684b60405d41"