doc: update documentation for fetchinvoice(7) and offer(7).

1. Don't refer to obsolete send_invoice flag.
2. Don't refer to obsolete quantity_min field.
3. Don't refer to unsigned vs signed offers: they're all unsigned.
4. Add references to invoicerequest(7).

Signed-off-by: Rusty Russell <[email protected]>

doc/lightning-fetchinvoice.7.md

@@ -19,13 +19,12 @@ If **fetchinvoice-noconnect** is not specified in the configuation, it
 will connect to the destination in the (currently common!) case where it
 cannot find a route which supports `option_onion_messages`.
 
-The offer must not contain *send\_invoice*; see lightning-sendinvoice(7).
-
-*amount\_msat* is required if the *offer* does not specify
-an amount at all, otherwise it is not allowed.
+*amount\_msat* is required if the *offer* does not specify an amount
+at all, otherwise it is optional (but presumably if you set it to less
+than the offer, you will get an error from the issuer).
 
 *quantity* is is required if the *offer* specifies
-*quantity\_min* or *quantity\_max*, otherwise it is not allowed.
+*quantity\_max*, otherwise it is not allowed.
 
 *recurrence\_counter* is required if the *offer*
 specifies *recurrence*, otherwise it is not allowed.
@@ -43,7 +42,8 @@ calls for the same recurrence, as it is used to link them together.
 *timeout* is an optional timeout; if we don't get a reply before this
 we fail (default, 60 seconds).
 
-*payer\_note* is an optional payer note to include in the fetched invoice.
+*payer\_note* is an optional payer note to ask the issuer to include
+in the fetched invoice.
 
 RETURN VALUE
 ------------

doc/lightning-offer.7.md

@@ -16,9 +16,8 @@ one), which is a precursor to creating one or more invoices.  It
 automatically enables the processing of an incoming invoice\_request,
 and issuing of invoices.
 
-Note that it creates two variants of the offer: a signed and an
-unsigned one (which is smaller).  Wallets should accept both: the
-current specification allows either.
+Note that for making an offer to *pay* someone else, see
+lightning-invoicerequest(7).
 
 The *amount* parameter can be the string "any", which creates an offer
 that can be paid with any amount (e.g. a donation).  Otherwise it can
@@ -41,7 +40,8 @@ The *issuer* is another (optional) field exposed in the offer, and
 reflects who is issuing this offer (i.e. you) if appropriate.
 
 The *label* field is an internal-use name for the offer, which can
-be any UTF-8 string.
+be any UTF-8 string.  This is *NOT* encoded in the offer not sent
+to the issuer.
 
 The presence of *quantity\_max* indicates that the
 invoice can specify more than one of the items up (and including)
@@ -124,7 +124,7 @@ Rusty Russell <<[email protected]>> is mainly responsible.
 SEE ALSO
 --------
 
-lightning-listoffers(7), lightning-disableoffer(7).
+lightning-listoffers(7), lightning-disableoffer(7), lightning-invoicerequest(7).
 
 RESOURCES
 ---------