[Helm Chart] Update pre-release doc URLs to point to staged documentation (#50569)

[prdai]

This PR updates the documentation links in Chart.yaml and values.yaml for Helm Chart pre-release candidates.
Previously, these links pointed to the production docs at https://airflow.apache.org, which is inconsistent with other pre-release artifacts (e.g., PyPI packages) that reference staged docs.

Changes in this PR:

• Update Helm Chart URLs to use https://airflow.staged.apache.org for pre-release builds.

related: #50569

[potiuk]

I don't think it's a good idea - how do you distinguish whether it's pre-release or not? We cannot really commit the code for pre-release / staging docs because we would have to somehow remember to bring them back to PROD - that's very, very brittle.

How it should be done - the links should be still "prod" - but they should be dynamically replaced with the staged build when .RC version of the chart is being prepared as release - so it should be part of the "breeze release-management" commands and code that is run to prepare the release, not committed to the repo

[HsiuChuanHsu]

Hi @Programmer-RD-AI,
I noticed this PR has been not updated for a while now.
Just wanted to check in and see if you're still working on it. If not, I'd be happy to take over.

Let me know what you think!

[prdai]

hi @HsiuChuanHsu please feel free to take over, i have been unable to look into this since the initial pr, thanks :) i will close the pr so that you can start?

[HsiuChuanHsu]

Thanks!