Update README

Author: jinzhu

README.md

@@ -1,3 +1,17 @@
-# gomerchant
+# Gomerchant
+
+Gomerchant is an abstracted payment interface for Golang, it provides unified API for different payment gateways.
+
+## Usage
+
+```go
+import "github.com/qor/gomerchant/gateways/stripe"
+
+func main() {
+  Stripe := stripe.New(&stripe.Config{
+    Key: config.Key,
+  })
+}
+```
 
 [![GoDoc](https://godoc.org/github.com/golang/gddo?status.svg)](http://godoc.org/github.com/qor/gomerchant)

credit_card_manager.go

@@ -51,7 +51,7 @@ type ListCreditCardsResponse struct {
 	Params
 }
 
-// CustomerCard
+// CustomerCreditCard CustomerCard defination
 type CustomerCreditCard struct {
 	CustomerID   string
 	CustomerName string