Fix comment typos

Author: raphael

client/client.go

@@ -16,7 +16,7 @@ import (
 )
 
 type (
-	// Client is the command client data structure for all goa service clients.
+	// Client is the common client data structure for all goa service clients.
 	Client struct {
 		// Client is the underlying http client.
 		*http.Client

middleware.go

@@ -17,7 +17,7 @@ type (
 //
 // - a goa middleware: goa.Middleware or func(goa.Handler) goa.Handler
 //
-// - a goa handler: goa.Handler or func(*goa.Context) error
+// - a goa handler: goa.Handler or func(context.Context, http.ResponseWriter, *http.Request) error
 //
 // - an http middleware: func(http.Handler) http.Handler
 //