bolt12: import latest spec (timestamp -> created_at).

@shesek points out that we called this field created_at in bolt11 decode,
which makes more sense anyway.

Changelog-EXPERIMENTAL: bolt12 decode `timestamp` field deprecated in favor of new name `created_at`.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

doc/lightning-decode.7

@@ -153,11 +153,11 @@ If \fBtype\fR is "bolt12 invoice", and \fBvalid\fR is \fItrue\fR:
 .IP \[bu]
 \fBdescription\fR (string): the description of the purpose of the offer
 .IP \[bu]
-\fBtimestamp\fR (u64): the UNIX timestamp of the invoice
+\fBcreated_at\fR (u64): the UNIX timestamp of invoice creation
 .IP \[bu]
 \fBpayment_hash\fR (hex): the hash of the \fIpayment_preimage\fR (always 64 characters)
 .IP \[bu]
-\fBrelative_expiry\fR (u32): the number of seconds after \fItimestamp\fR when this expires
+\fBrelative_expiry\fR (u32): the number of seconds after \fIcreated_at\fR when this expires
 .IP \[bu]
 \fBmin_final_cltv_expiry\fR (u32): the number of blocks required by destination
 .IP \[bu]
@@ -256,7 +256,7 @@ the following warnings are possible:
 .IP \[bu]
 \fBwarning_invoice_missing_recurrence_basetime\fR: Has \fBrecurrence_counter\fR without \fBrecurrence_basetime\fR
 .IP \[bu]
-\fBwarning_invoice_missing_timestamp\fR: Missing \fBtimestamp\fR
+\fBwarning_invoice_missing_created_at\fR: Missing \fBcreated_at\fR
 .IP \[bu]
 \fBwarning_invoice_missing_payment_hash\fR: Missing \fBpayment_hash\fR
 .IP \[bu]
@@ -414,4 +414,4 @@ Rusty Russell \fI<rusty@rustcorp.com.au\fR> is mainly responsible\.
 
 Main web site: \fIhttps://github.com/ElementsProject/lightning\fR
 
-\" SHA256STAMP:cd54af7c631f06b3db72848cdf90951ceb14d89b8bca981dba69244cd2ddbae5
+\" SHA256STAMP:dda6e1cff3e58c38b637c5a11673b5a9f4837cbdf89ed3be52a8bfc874af87d4

doc/lightning-decode.7.md

@@ -70,9 +70,9 @@ If **type** is "bolt12 invoice", and **valid** is *true*:
   - **signature** (bip340sig): BIP-340 signature of the *node_id* on this offer
   - **amount_msat** (msat): the amount in bitcoin
   - **description** (string): the description of the purpose of the offer
-  - **timestamp** (u64): the UNIX timestamp of the invoice
+  - **created_at** (u64): the UNIX timestamp of invoice creation
   - **payment_hash** (hex): the hash of the *payment_preimage* (always 64 characters)
-  - **relative_expiry** (u32): the number of seconds after *timestamp* when this expires
+  - **relative_expiry** (u32): the number of seconds after *created_at* when this expires
   - **min_final_cltv_expiry** (u32): the number of blocks required by destination
   - **offer_id** (hex, optional): the id of this offer (merkle hash of non-signature fields) (always 64 characters)
   - **chains** (array of hexs, optional): which blockchains this offer is for (missing implies bitcoin mainnet only):
@@ -108,7 +108,7 @@ If **type** is "bolt12 invoice", and **valid** is *false*:
     - **warning_invoice_missing_blinded_payinfo**: Has **paths** without payinfo
     - **warning_invoice_invalid_blinded_payinfo**: Does not have exactly one payinfo for each of **paths**
     - **warning_invoice_missing_recurrence_basetime**: Has **recurrence_counter** without **recurrence_basetime**
-    - **warning_invoice_missing_timestamp**: Missing **timestamp**
+    - **warning_invoice_missing_created_at**: Missing **created_at**
     - **warning_invoice_missing_payment_hash**: Missing **payment_hash**
     - **warning_invoice_refund_signature_missing_payer_key**: Missing **payer_key** for refund_signature
     - **warning_invoice_refund_signature_invalid**: **refund_signature** incorrect
@@ -183,4 +183,4 @@ RESOURCES
 
 Main web site: <https://github.com/ElementsProject/lightning>
 
-[comment]: # ( SHA256STAMP:8ca0b9178b8ea6575cd80291001263dc27f721664648086a7c1a02efcb545ee7)
+[comment]: # ( SHA256STAMP:fbbfc116c23489d4f346b4d5eb06dd922592c543ec68e5a76b6822b2658bd46d)

doc/schemas/decode.schema.json

@@ -263,7 +263,7 @@
 		}
 	    },
 	    "then": {
-		"required": [ "node_id", "signature", "amount_msat", "description", "timestamp", "payment_hash", "relative_expiry", "min_final_cltv_expiry" ],
+		"required": [ "node_id", "signature", "amount_msat", "description", "created_at", "payment_hash", "relative_expiry", "min_final_cltv_expiry" ],
 		"additionalProperties": false,
 		"properties": {
 		    "type": { },
@@ -378,8 +378,11 @@
 			"description": "the payer-provided blob to derive payer_key"
 		    },
 		    "timestamp": {
+			"deprecated": true
+		    },
+		    "created_at": {
 			"type": "u64",
-			"description": "the UNIX timestamp of the invoice"
+			"description": "the UNIX timestamp of invoice creation"
 		    },
 		    "payment_hash": {
 			"type": "hex",
@@ -389,7 +392,7 @@
 		    },
 		    "relative_expiry": {
 			"type": "u32",
-			"description": "the number of seconds after *timestamp* when this expires"
+			"description": "the number of seconds after *created_at* when this expires"
 		    },
 		    "min_final_cltv_expiry": {
 			"type": "u32",
@@ -462,6 +465,7 @@
 		    "payer_key": { },
 		    "payer_info": { },
 		    "timestamp": { },
+		    "created_at": { },
 		    "payment_hash": { },
 		    "relative_expiry": { },
 		    "min_final_cltv_expiry": { },
@@ -487,9 +491,9 @@
 			"type": "string",
 			"description": "Has **recurrence_counter** without **recurrence_basetime**"
 		    },
-		    "warning_invoice_missing_timestamp": {
+		    "warning_invoice_missing_created_at": {
 			"type": "string",
-			"description": "Missing **timestamp**"
+			"description": "Missing **created_at**"
 		    },
 		    "warning_invoice_missing_payment_hash": {
 			"type": "string",