Add links to open tracking issues

I read through the 0.6 docs, and found a few places that could benefit from linking to tracking issues, for interested users to subscribe to or help with.

Examples:

> We plan to build additional server features in the future and only support `axum` to ship faster.
https://github.com/DioxusLabs/docsite/blob/2ec11f638ce712baa55e8f935aebb2e657f3086c/docs-src/0.6/src/guide/backend.md?plain=1#L65

> In the future, Dioxus might add OpenSSL's vendored feature implicitly to make this error go away.
https://github.com/DioxusLabs/docsite/blob/2ec11f638ce712baa55e8f935aebb2e657f3086c/docs-src/0.6/src/guide/bundle.md?plain=1#L88

> As of today, `dx bundle` only builds desktop apps for the native platform and architecture.
https://github.com/DioxusLabs/docsite/blob/2ec11f638ce712baa55e8f935aebb2e657f3086c/docs-src/0.6/src/guide/bundle.md?plain=1#L146

> Shadcn-ui: Not yet, a radix-ui port to Dioxus is underway but we're not done yet.
https://github.com/DioxusLabs/docsite/blob/2ec11f638ce712baa55e8f935aebb2e657f3086c/docs-src/0.6/src/guide/next_steps.md?plain=1#L53

> Static-site-generation: Yes! The docs are currently under construction, so stay tuned. 🏗️https://github.com/DioxusLabs/docsite/blob/2ec11f638ce712baa55e8f935aebb2e657f3086c/docs-src/0.6/src/guide/next_steps.md?plain=1#L55