Fix: Fix the doc of `txprepare`. Add the description of some parameters.

doc/lightning-txprepare.7

@@ -31,14 +31,31 @@ number, a whole number ending in \fIsat\fR, a whole number ending in \fI000msat\
 or a number with 1 to 8 decimal places ending in \fIbtc\fR\.
 
 
-\fBtxprepare\fR is similar to the first part of a \fBwithdraw\fR command, but
-supports multiple outputs and uses \fIoutputs\fR as parameter\. The second part
-is provided by \fBtxsend\fR\.
+\fIfeerate\fR is an optional feerate to use\. It can be one of the strings
+\fIurgent\fR (aim for next block), \fInormal\fR (next 4 blocks or so) or \fIslow\fR
+(next 100 blocks or so) to use lightningd’s internal estimates: \fInormal\fR
+is the default\.
+
+
+Otherwise, \fIfeerate\fR is a number, with an optional suffix: \fIperkw\fR means
+the number is interpreted as satoshi-per-kilosipa (weight), and \fIperkb\fR
+means it is interpreted bitcoind-style as satoshi-per-kilobyte\. Omitting
+the suffix is equivalent to \fIperkb\fR\.
+
+
+\fIminconf\fR specifies the minimum number of confirmations that used
+outputs should have\. Default is 1\.
 
 
 \fIutxos\fR specifies the utxos to be used to fund the transaction, as an array
 of "txid:vout"\. These must be drawn from the node's available UTXO set\.
 
+
+\fBtxprepare\fR is similar to the first part of a \fBwithdraw\fR command, but
+supports multiple outputs and uses \fIoutputs\fR as parameter\. The second part
+is provided by \fBtxsend\fR\.
+
+
 .SH RETURN VALUE
 
 On success, an object with attributes \fIunsigned_tx\fR and \fItxid\fR will be

doc/lightning-txprepare.7.md

@@ -29,13 +29,26 @@ all available funds. Otherwise, it is in amount precision; it can be a whole
 number, a whole number ending in *sat*, a whole number ending in *000msat*,
 or a number with 1 to 8 decimal places ending in *btc*.
 
-**txprepare** is similar to the first part of a **withdraw** command, but
-supports multiple outputs and uses *outputs* as parameter. The second part
-is provided by **txsend**.
+*feerate* is an optional feerate to use. It can be one of the strings
+*urgent* (aim for next block), *normal* (next 4 blocks or so) or *slow*
+(next 100 blocks or so) to use lightningd’s internal estimates: *normal*
+is the default.
+
+Otherwise, *feerate* is a number, with an optional suffix: *perkw* means
+the number is interpreted as satoshi-per-kilosipa (weight), and *perkb*
+means it is interpreted bitcoind-style as satoshi-per-kilobyte. Omitting
+the suffix is equivalent to *perkb*.
+
+*minconf* specifies the minimum number of confirmations that used
+outputs should have. Default is 1.
 
 *utxos* specifies the utxos to be used to fund the transaction, as an array
 of "txid:vout". These must be drawn from the node's available UTXO set.
 
+**txprepare** is similar to the first part of a **withdraw** command, but
+supports multiple outputs and uses *outputs* as parameter. The second part
+is provided by **txsend**.
+
 RETURN VALUE
 ------------