Fix spelling error

discovercard_client.go

@@ -20,7 +20,7 @@ type DiscoverCardClient struct {
 }
 
 // NewDiscoverCardClient returns a Client interface configured to handle
-// Discover Card's brand of idiosyncracy
+// Discover Card's brand of idiosyncrasy
 func NewDiscoverCardClient(bc *BasicClient) Client {
 	return &DiscoverCardClient{bc}
 }

vanguard_client.go

@@ -15,7 +15,7 @@ type VanguardClient struct {
 }
 
 // NewVanguardClient returns a Client interface configured to handle Vanguard's
-// brand of idiosyncracy
+// brand of idiosyncrasy
 func NewVanguardClient(bc *BasicClient) Client {
 	return &VanguardClient{bc}
 }