Fix links to OSRA Program Charter and ROS Project Charter (backport #7193)

[mergify]

Description

I found that the links don't work:

1. https://osralliance.org/staging/wp-content/uploads/2024/03/OSRA-Program-Charter.pdf
2. https://osralliance.org/staging/wp-content/uploads/2024/03/ros_project_charter.pdf

I found these links on the OSRA website's Governance page: https://osralliance.org/governance/

1. https://cuu.qwj.mybluehost.me/wp-content/uploads/2024/03/OSRA-Program-Charter.pdf
2. https://cuu.qwj.mybluehost.me/wp-content/uploads/2024/03/ros_project_charter.pdf

and then I figured out that removing the staging/ level fixed the osralliance.org/ links, which seems better to me.

Did you use Generative AI?

Additional Information

Backport to all active distros.

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This is an automatic backport of pull request #7193 done by Mergify.

[github-actions]

HTML artifacts: https://github.com/ros2/ros2_documentation/actions/runs/35518278652/artifacts/10607776924.

To view the resulting site:

1. Click on the above link to download the artifacts archive
2. Extract it
3. Open html-artifacts-7197/index.html in your favorite browser