fix gh-pages homepage

### Description

Currently, the `javadocs` link in the [readme](https://github.com/getsentry/sentry-java?tab=readme-ov-file#useful-links-and-docs) leads to a [dead page](https://getsentry.github.io/sentry-java/). There already is a [deployment going on](https://github.com/getsentry/sentry-java/tree/gh-pages), it's just that the modules overview isn't there.