docs(plugin-iceberg): Supplement documentation for transaction support

[hantangwangd]

Description

This PR supplements the documentation for Iceberg transaction support, adding descriptions for the following two features:

• multi-table read, single-table write capability under snapshot isolation
• read-your-writes visibility semantics in uncommitted transactions

Motivation and Context

Add more details about Iceberg transaction features

Impact

N/A

Test Plan

N/A

Contributor checklist

• Please make sure your submission complies with our contributing guide, in particular code style and commit standards.
• PR description addresses the issue accurately and concisely. If the change is non-trivial, a GitHub Issue is referenced.
• Documented new properties (with its default value), SQL syntax, functions, or other functionality.
• If release notes are required, they follow the release notes guidelines.
• Adequate tests were added if applicable.
• CI passed.
• If adding new dependencies, verified they have an OpenSSF Scorecard score of 5.0 or higher (or obtained explicit TSC approval for lower scores).

Release Notes

== NO RELEASE NOTE ==

Summary by Sourcery

Update Iceberg connector documentation to describe additional transaction semantics and capabilities.

Documentation:

• Document snapshot isolation support for multi-table reads with single-table writes in Iceberg transactions.
• Describe read-your-writes visibility semantics for uncommitted Iceberg transactions.

[sourcery-ai]

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

Updates the Iceberg connector documentation to describe transaction semantics, specifically multi-table read/single-table write behavior under snapshot isolation and read-your-writes visibility for uncommitted transactions.

File-Level Changes

Change	Details	Files
Document Iceberg transaction semantics and capabilities.	Expand the Iceberg connector docs to describe supported multi-table read and single-table write patterns under snapshot isolation. Clarify read-your-writes visibility guarantees within a single uncommitted transaction. Integrate the new transactional behavior descriptions into the existing transactions/consistency section for the Iceberg connector.	presto-docs/src/main/sphinx/connector/iceberg.rst

---

Tips and commands

Interacting with Sourcery

• Trigger a new review: Comment @sourcery-ai review on the pull request.
• Continue discussions: Reply directly to Sourcery's review comments.
• Generate a GitHub issue from a review comment: Ask Sourcery to create an
  issue from a review comment by replying to it. You can also reply to a
  review comment with @sourcery-ai issue to create an issue from it.
• Generate a pull request title: Write @sourcery-ai anywhere in the pull
  request title to generate a title at any time. You can also comment
  @sourcery-ai title on the pull request to (re-)generate the title at any time.
• Generate a pull request summary: Write @sourcery-ai summary anywhere in
  the pull request body to generate a PR summary at any time exactly where you
  want it. You can also comment @sourcery-ai summary on the pull request to
  (re-)generate the summary at any time.
• Generate reviewer's guide: Comment @sourcery-ai guide on the pull
  request to (re-)generate the reviewer's guide at any time.
• Resolve all Sourcery comments: Comment @sourcery-ai resolve on the
  pull request to resolve all Sourcery comments. Useful if you've already
  addressed all the comments and don't want to see them anymore.
• Dismiss all Sourcery reviews: Comment @sourcery-ai dismiss on the pull
  request to dismiss all existing Sourcery reviews. Especially useful if you
  want to start fresh with a new review - don't forget to comment
  @sourcery-ai review to trigger a new review!

Customizing Your Experience

Access your dashboard to:

• Enable or disable review features such as the Sourcery-generated pull request
  summary, the reviewer's guide, and others.
• Change the review language.
• Add, remove or edit custom review instructions.
• Adjust other review settings.

Getting Help

• Contact our support team for questions or feedback.
• Visit our documentation for detailed guides and information.
• Keep in touch with the Sourcery team by following us on X/Twitter, LinkedIn or GitHub.

[sourcery-ai]

Hey - I've reviewed your changes and they look great!

---

Sourcery is free for open source - if you like our reviews please consider sharing them ✨

• X
• Mastodon
• LinkedIn
• Facebook

_{Help me be more useful! Please click 👍 or 👎 on each comment and I'll use the feedback to improve your reviews.}

[steveburnett]

LGTM! (docs)

Pull branch, local doc build, looks good. Thanks!