I added the caveat so that the formula sticks as closely to the original package as possible. The original install.sh script from the package contains these lines

```bash
# create ssh private key if it does not exist
test -e ~/.ssh/id_rsa || ssh-keygen -q -t rsa -f ~/.ssh/id_rsa -N ""
```

What do you think about changing the caveat to simply `By default, the ~/.ssh/id_rsa key will be used by appscale-tools` ?