[docs] Add documentation for offset configuration and session properties

[steveburnett]

Description

Add doc for offset-clause-enabled and offset_clause_enabled configuration and session properties. Fixes #25453.

Motivation and Context

In a comment on #25216, @xieandrew mentioned
Separately, it may be important to document the offset_clause_enabled session prop and offset-clause-enabled configuration prop since those are needed by the user to actually use the main feature this fix relates to. I only see those properties in a release note: https://prestodb.io/docs/current/release/release-0.257.html#general-changes.

Impact

Documentation.

Test Plan

Local doc builds. Screenshots:

Configuration property offset-clause-enabled

Session property offset_clause_enabled

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.

Release Notes

== NO RELEASE NOTE ==

[hantangwangd]

@steveburnett Thanks for adding this, lgtm!