Correct sample-btcd.conf RPC listen comment.
Correct sample-btcd.conf RPC listen comment.

The comment for the RPC listen section in the sample-btcd.conf incorrectly
claimed that the default for the RPC server listener is to listen on all
interfaces by default.  In reality, it only listens on localhost for IPv4
and IPv6 by default.

Closes #208.

jrick/btcd,adiabat/btcd,aakselrod/btcd,Dirbaio/btcd,runeaune/btcd,danoctavian/btcd,runeaune/btcd,jongillham/btcd,ltcsuite/ltcd,btcsuitereleases/btcd,FactomProject/btcd,davecgh/btcd,sysbot/btcd,dan-da/btcd,tb00/btcd,jrick/btcd,jcmincke/dcrd,dajohi/btcd,Cleawing/btcd,FactomProject/btcd,ppcsuite/ppcd-old,jimmysong/btcd,mathiasrw/btcd,adiabat/btcd,Roasbeef/btcd,Dirbaio/btcd,CryptocurrencyCabal/htcd,glv2/ppcd,jcmincke/dcrd,CryptocurrencyCabal/htcd,1d4Nf6/btcd,btcsuite/btcd,BitGo/prova,mathiasrw/btcd,stevenroose/btcd,pkothbauer/btcd,jcmincke/dcrd,soapboxsys/ombfullnode,dajohi/btcd,qchain/btcd,jongillham/btcd,ppcsuite/ppcd,pkothbauer/btcd,wallclockbuilder/btcd,Cleawing/btcd,ppcsuite/ppcd-old,dajohi/btcd,DanielKrawisz/btcd,stevenroose/btcd,dan-da/btcd,btcsuite/btcd,btcsuitereleases/btcd,jrick/dcrd,soapboxsys/ombfullnode,jrick/dcrd,cjepson/btcd,wallclockbuilder/btcd,DanielKrawisz/btcd,cqswxj2013/btcd,Dirbaio/btcd,qchain/btcd,Stash-Crypto/btcd,BitGo/prova,Roasbeef/btcd,sysbot/btcd,jrick/btcd,davecgh/btcd,ltcsuite/ltcd,Stash-Crypto/btcd,hectorj/btcd,glv2/ppcd,toddfries/btcd,1d4Nf6/btcd,decred/dcrd,jimmysong/btcd,aakselrod/btcd,tb00/btcd,danoctavian/btcd,cjepson/btcd,hectorj/btcd,toddfries/btcd,ppcsuite/ppcd,decred/dcrd,cqswxj2013/btcd