doc: fundchannel command, clarify optional `feerate`

mentioned in issue #2354

doc/lightning-fundchannel.7

@@ -2,12 +2,12 @@
 .\"     Title: lightning-fundchannel
 .\"    Author: [FIXME: author] [see http://docbook.sf.net/el/author]
 .\" Generator: DocBook XSL Stylesheets v1.79.1 <http://docbook.sf.net/>
-.\"      Date: 01/22/2019
+.\"      Date: 02/15/2019
 .\"    Manual: \ \&
 .\"    Source: \ \&
 .\"  Language: English
 .\"
-.TH "LIGHTNING\-FUNDCHANN" "7" "01/22/2019" "\ \&" "\ \&"
+.TH "LIGHTNING\-FUNDCHANN" "7" "02/15/2019" "\ \&" "\ \&"
 .\" -----------------------------------------------------------------
 .\" * Define some portability stuff
 .\" -----------------------------------------------------------------
@@ -40,7 +40,7 @@ The \fBfundchannel\fR RPC command opens a payment channel with a peer by committ
 .sp
 \fIsatoshi\fR is the amount in satoshis taken from the internal wallet to fund the channel\&. The string \fIall\fR can be used to specify all available funds (or 16777215 satoshi if more is available)\&. The value cannot be less than the dust limit, currently set to 546, nor more than 16777215 satoshi\&.
 .sp
-\fIfeerate\fR is an optional feerate to use\&. It can be one of the strings \fIurgent\fR, \fInormal\fR or \fIslow\fR to use lightningd\(cqs internal estimates: \fInormal\fR is the default\&.
+\fIfeerate\fR is an optional feerate used for the opening transaction and as initial feerate for commitment and HTLC transactions\&. It can be one of the strings \fIurgent\fR, \fInormal\fR or \fIslow\fR to use lightningd\(cqs internal estimates: \fInormal\fR is the default\&.
 .sp
 \fIannounce\fR is an optional flag that triggers whether to announce this channel or not\&. Defaults to true\&. An unannounced channel is considered private\&.
 .sp

doc/lightning-fundchannel.7.txt

@@ -27,7 +27,8 @@ The string 'all' can be used to specify all available funds (or 16777215 satoshi
 The value cannot be less than the dust limit, currently set to 546, nor more
 than 16777215 satoshi.
 
-'feerate' is an optional feerate to use.  It can be one of the strings
+'feerate' is an optional feerate used for the opening transaction and as initial feerate for
+commitment and HTLC transactions.  It can be one of the strings
 'urgent', 'normal' or 'slow' to use lightningd's internal estimates:
 'normal' is the default.