GH-49723: [C++][FlightRPC][ODBC] Update ODBC Documentation

[justing-bq]

Rationale for this change

Update ODBC Documentation in preparation for public release.
Resolves #49723

What changes are included in this PR?

Miscellaneous doc changes.

Are these changes tested?

N/A

Are there any user-facing changes?

No

• GitHub Issue: [C++][FlightRPC][ODBC] Documentation: Connection Options for Unix Systems #49723

[github-actions]

Thanks for opening a pull request!

If this is not a minor PR. Could you open an issue for this pull request on GitHub? https://github.com/apache/arrow/issues/new/choose

Opening GitHub issues ahead of time contributes to the Openness of the Apache Arrow project.

Then could you also rename the pull request title in the following format?

GH-${GITHUB_ISSUE_ID}: [${COMPONENT}] ${SUMMARY}

or

MINOR: [${COMPONENT}] ${SUMMARY}

See also:

• Other pull requests
• Contribution Guidelines - Contributing Overview

[github-actions]

⚠️ GitHub issue #49723 has been automatically assigned in GitHub to PR creator.

[justing-bq]

@lidavidm @kou
Please take a look when you have time.