fix readme typo
fix readme typo

whichdigital/active-rest-client,andyjeffries/flexirest,MatthieuKopec/active-rest-client,chibicode/active-rest-client,chenhang/active-rest-client,andyjeffries/active-rest-client,djpate/active-rest-client,MoKuH/active-rest-client,nathanhoel/active-rest-client