Add C++ template app and tutorial to SDK docs

[dacharyc]

Pull Request Info - SDK Docs Consolidation

Staged Pages

• C++ Landing Page: Add "Learning Paths" section with links to the C++ quick start, template app, and tutorial, similar to the other SDKs.
• Example Projects: Add C++ to the list of SDK example apps.

Release Notes

• C++ SDK

  • Landing Page: Add "Learning Paths" section with links to the C++ quick start, template app, and tutorial.

• Example Projects: Add the C++ template app to the SDK template app list.

[github-actions[bot]]

Readability for Commit Hash: 72c02fc9ad8ef4a548e81ea5f0d7fe5c12885b9b

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: Grade Level: 9.1, Reading Ease: 50.94

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: 4172b71e22a838c3493282588423c8fbb0e6118e