[docs] added documentation for string interpolation in readme
[docs] added documentation for string interpolation in readme

whismat/winston,winstonjs/winston,auth0/winston,megastef/winston,aquavitae/winston,unlucio/winston,uber/winston,DenisGorbachev/winston,dustinblackman/winston,alinex/winston,SmartNode-es/winston,rakesh-mohanta/winston,beni55/winston,thaliproject/winston,winstonjs/winston,alphagov/winston,harriha/winston,tobli/winston,jjmleiro/winston,modulexcite/winston,s-panferov/winston,wancharle/winston,get-trucked/winston,psquickitjayant/winston,z-10/winston,dbmikus/winston,paulhroth/winston,nikolas/winston