windows build script: add note to build from fresh clone
windows build script: add note to build from fresh clone

spesmilo/electrum,vialectrum/vialectrum,pooler/electrum-ltc,vialectrum/vialectrum,wakiyamap/electrum-mona,fujicoin/electrum-fjc,spesmilo/electrum,neocogent/electrum,fujicoin/electrum-fjc,wakiyamap/electrum-mona,vialectrum/vialectrum,spesmilo/electrum,fujicoin/electrum-fjc,pooler/electrum-ltc,pooler/electrum-ltc,wakiyamap/electrum-mona,wakiyamap/electrum-mona,spesmilo/electrum,neocogent/electrum,pooler/electrum-ltc,neocogent/electrum