Exclude the overview.html javadoc file from source

[starksm64]

Fixes #734

[manovotn]

According to the issue, this seems rather as a problem with the Jenkins setup then the repo itself? IIUIC, what you're adding would just exclude our own file.
It's also curious that this only happens for the API artifact and not for lang model or EL API 🤔

[Azquelt]

I had a look into why this happens. I think it's because we're listing the overview.html as a resource, which is really declaring that it should be included in the output jar. However, for some reason, when targetPath is an absolute path, it doesn't get included in the main jar with that path but does get included in the sources jar. 😕

It looks like it's only been included as a resource in order to enable filtering to replace placeholders in the file? I've made a PR to do this with a separate goal rather than including it as a resource: #745

[Azquelt]

This also explains why it doesn't appear in the EL API, that overview file hasn't had placeholders added and isn't configured as a resource.