docs: fix references in public docs

[JosephLenton]

Which issue does this PR close?

• Closes Fix current docs build issues #2938

What changes are included in this PR?

• Links to external sites are made clickable. This is changing from https://example.com to <https://example.com>.
• References to internal APIs are removed. The comment is the same, but the doc link is gone.
• Trailing triple slash opening a code snippet, but never closing it, are removed.

The following items were previously mentioned in the docs, but were not public. They are now publicaly exported:

iceberg::transaction::ExpireSnapshotsAction
iceberg::transaction::FastAppendAction
iceberg::transaction::ReplaceSortOrderAction
iceberg::transaction::UpdateLocationAction
iceberg::transaction::UpdatePropertiesAction
iceberg::transaction::UpdateSchemaAction
iceberg::transaction::UpdateStatisticsAction
iceberg::transaction::UpgradeFormatVersionAction
iceberg::transaction::TransactionAction
iceberg::JoinHandle

Are these changes tested?

These changes were QA'd by running cargo doc --no-deps.

AI Disclosure

I got Claude to do most of the changes in this PR.

[dannycjones]

Thanks for this change, @JosephLenton! I think it's important that we maintain good hygiene on the docs.

I think there's a few things highlighted by the lints where we're better addressing the root cause. For example: types that we thought were public but actually aren't, and need exporting.

[JosephLenton]

Hey @dannycjones I have updated the PR to now export all of the bits I could find, and made further updates to the docs.

When you get time could you please give this a second review.