lightningd: fix type of listhtlcs payment_hash.

`hash` is a tighter requirement than simply `hex`.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

doc/lightning-listhtlcs.7.md

@@ -26,7 +26,7 @@ On success, an object containing **htlcs** is returned.  It is an array of objec
 - **expiry** (u32): the block number where this HTLC expires/expired
 - **amount\_msat** (msat): the value of the HTLC
 - **direction** (string): out if we offered this to the peer, in if they offered it (one of "out", "in")
-- **payment\_hash** (hex): payment hash sought by HTLC (always 64 characters)
+- **payment\_hash** (hash): payment hash sought by HTLC
 - **state** (string): The first 10 states are for `in`, the next 10 are for `out`. (one of "SENT\_ADD\_HTLC", "SENT\_ADD\_COMMIT", "RCVD\_ADD\_REVOCATION", "RCVD\_ADD\_ACK\_COMMIT", "SENT\_ADD\_ACK\_REVOCATION", "RCVD\_REMOVE\_HTLC", "RCVD\_REMOVE\_COMMIT", "SENT\_REMOVE\_REVOCATION", "SENT\_REMOVE\_ACK\_COMMIT", "RCVD\_REMOVE\_ACK\_REVOCATION", "RCVD\_ADD\_HTLC", "RCVD\_ADD\_COMMIT", "SENT\_ADD\_REVOCATION", "SENT\_ADD\_ACK\_COMMIT", "RCVD\_ADD\_ACK\_REVOCATION", "SENT\_REMOVE\_HTLC", "SENT\_REMOVE\_COMMIT", "RCVD\_REMOVE\_REVOCATION", "RCVD\_REMOVE\_ACK\_COMMIT", "SENT\_REMOVE\_ACK\_REVOCATION")
 
 [comment]: # (GENERATE-FROM-SCHEMA-END)
@@ -46,4 +46,4 @@ RESOURCES
 
 Main web site: <https://github.com/ElementsProject/lightning>
 
-[comment]: # ( SHA256STAMP:2f658fb394c49408c60c03b396bbc5afe7465fd33f48d8043233f2fe2b76f25e)
+[comment]: # ( SHA256STAMP:990e36b109c9e318bc566a951ce0d39032e252cdd1555c75ad7b168d547c937f)

doc/schemas/listhtlcs.schema.json

@@ -46,10 +46,8 @@
             "description": "out if we offered this to the peer, in if they offered it"
           },
           "payment_hash": {
-            "type": "hex",
-            "description": "payment hash sought by HTLC",
-            "maxLength": 64,
-            "minLength": 64
+            "type": "hash",
+            "description": "payment hash sought by HTLC"
           },
           "state": {
             "type": "string",