Add tools deps usage notes to README

[lread]

This project depends on native dep org.graalvm.nativeimage/svm.

While technically correct, tools deps does not support native deps and fails for this native dep.

Since the native dep is provided by the Graal installation anyway, it can be safely excluded for tools deps.

[borkdude]

Can you add the comment you made in this issue to the README as well? That seems pretty informative.

[lread]

Ya, good idea, done.

[borkdude]

Thanks!