Docs: Fix links of `Get Started` and `Community` sections in footer

[wayneguow]

Apache Iceberg version

main (development)

Query engine

None

Please describe the bug 🐞

When browsing iceberg non-home pages, if you click on the links of the Get Started and Community sections in the footer, the jump will fail.
For example:
If the current page you are browsing is: https://iceberg.apache.org/docs/nightly/#open-standard, if click Spark Quickstart, the jump link is https://iceberg.apache.org/docs/nightly/spark-quickstart, you will get a 404 Not Found error.

[github-actions]

This issue has been automatically marked as stale because it has been open for 180 days with no activity. It will be closed in next 14 days if no further activity occurs. To permanently prevent this issue from being considered stale, add the label 'not-stale', but commenting on the issue is preferred when possible.

[github-actions]

This issue has been closed because it has not received any activity in the last 14 days since being marked as 'stale'