Add .env.sample to make things clear that which env is needed
Add .env.sample to make things clear that which env is needed

dlanileonardo/step-pretty-slack-notify,dlanileonardo/step-pretty-slack-notify,dlanileonardo/step-pretty-slack-notify,wantedly/step-pretty-slack-notify,wantedly/step-pretty-slack-notify,wantedly/step-pretty-slack-notify