feat: update go boilerplate

go/README.md

@@ -3,19 +3,19 @@
 - Run :
 
 ```shell
-go run texttest_fixture.go gilded-rose.go
+go run texttest_fixture.go [<number-of-days>; default: 2]
 ```
 
 - Run tests :
 
 ```shell
-go test
+go test ./...
 ```
 
 - Run tests and coverage :
 
 ```shell
-go test -coverprofile=coverage.out
+go test ./... -coverprofile=coverage.out
 
 go tool cover -html=coverage.out
 ```