Initial version 0.0.0 means pre-major options are not respected

If packages initially start at `0.0.0` and you set the pre-major options to `true` they are not respected and you end up with a 1.0.0 release recommendation.

`release-please-config.json`

```json
{
"release-type": "node",
"bump-patch-for-minor-pre-major": true,
"bump-minor-pre-major": true,
"packages": {
"foo": {}
}
}
```

`.release-please-manifest.json`

```json
{
"foo": "0.0.0"
}
```

The PR opened will bump foo to 1.0.0. If you change the manifest version to `0.0.1` it works as expected. While it is an easy workaround, it took a while to realize the cause. I guess documentation could resolve it, but also I think this could be fixed to just bump to `0.0.1|0.1.0`.