fix transport and change tag

18.md

@@ -25,7 +25,7 @@ A Payment Request is defined as follows
   "r": bool <optional>,
   "m": Array[str] <optional>,
   "d": str <optional>,
-  "t": Transport
+  "t": Array[Transport]
 }
 ```
 
@@ -63,9 +63,9 @@ The supported transport types are:
 
 - type: `nostr`
 - target: `<nprofile>`
-- tags: `[["NIP-04", "true"], ["NIP-17", "true"]]`
+- tags: `[["m", "NIP-04"],["m", "NIP-17"]]`
 
-The payment request MUST specify which type of Nostr message they support in the `tags`. For [NIP-04](https://github.com/nostr-protocol/nips/blob/master/04.md) and [NIP-17](https://github.com/nostr-protocol/nips/blob/master/17.md) direct messages, the sender sends a `PaymentRequestPayload` as the message content. 
+The `m` tag MUST specify at least one type of Nostr direct message type the receiver supports. For [NIP-04](https://github.com/nostr-protocol/nips/blob/master/04.md) and [NIP-17](https://github.com/nostr-protocol/nips/blob/master/17.md) direct messages, the sender sends a `PaymentRequestPayload` as the message content. 
 
 Note that the use of NIP-04 direct messages is strongly discouraged, since it reveals metadata about sender and receiver public keys.