update README with slightly clearer instructions for building additional texts
update README with slightly clearer instructions for building additional texts

explorigin/browserbible-3,kidaa/uw-web,unfoldingWord-dev/uw-web,unfoldingWord-dev/uw-web,digitalbiblesociety/browserbible-3,unfoldingWord-dev/uw-web,digitalbiblesociety/browserbible-3,unfoldingWord-dev/uw-web,digitalbiblesociety/browserbible-3,unfoldingWord-dev/uw-web,kidaa/uw-web,explorigin/browserbible-3,kidaa/uw-web,kidaa/uw-web,kidaa/uw-web,explorigin/browserbible-3