C++: Add generated Set snippet to the supported types table

[dacharyc]

Pull Request Info

Noticed this quick fix while I was putting together release notes.

Staged Changes

• Supported Types

Reminder Checklist

If your PR modifies the docs, you might need to also update some corresponding
pages. Check if completed or N/A.

• Create Jira ticket for corresponding docs-app-services update(s), if any
• Checked/updated Admin API
• Checked/updated CLI reference

Review Guidelines

REVIEWING.md

[github-actions]

Readability for Commit Hash: 3e86939

You can see any previous Readability scores (if they exist) by looking
at the comment's history.

Readability scores for changed documents:

• source/sdk/cpp/model-data/supported-types: Grade Level: 14.2, Reading Ease: 32.43

For Grade Level, aim for 8 or below.

For Reading Ease scores, aim for 60 or above:

Score	Difficulty
90-100	Very Easy
80-89	Easy
70-79	Fairly Easy
60-69	Medium
50-59	Fairly Hard
30-49	Hard
0-29	Very Hard

For help improving readability, try Hemingway App.

[docs-builder-bot]

✨ Staging URL: https://preview-mongodbmongodb.gatsbyjs.io/realm/master/

🪵 Logs

• job log: 9a209c229f1f7703db39edc9c284b23d45b5155c