docs(preset): update preset configuration documentation for search API

[tharropoulos]

Change Summary

The documentation showed a default preset example for multi search presets. This PR addressed it and adds tip section to inform users about multi search presets.

Changes

• Modify example to show single-search preset structure
• Add tip section explaining multi-search preset option
• Recommend using single-search presets for flexibility
• Update code examples in JavaScript, Dart, and Shell

PR Checklist

• [x] I have read and signed the Contributor License Agreement.