fix typo in package.json
fix typo in package.json

warning gocryptotrader-web@0.4.0: Potential typo "contributers", did you mean "contributors"?
thrasher-/gocryptotrader,thrasher-/gocryptotrader,jmaurice/gocryptotrader,thrasher-/gocryptotrader,thrasher-/gocryptotrader,thrasher-/gocryptotrader