Add a new section to Suite document to explain extending with custom module entities

[EngincanV]

Description

Resolves https://github.com/volosoft/vs-internal/issues/8033

Checklist

• I fully tested it as developer / designer and created unit / integration tests
• I documented it (or no need to document or I will create a separate documentation issue)

[Copilot]

Pull request overview

This pull request adds a new documentation section explaining how to extend ABP Suite to recognize and list entities from custom modules (beyond ABP's built-in modules). This enhancement addresses the need for developers working with custom modules who want to establish navigation properties with entities from those modules.

Changes:

• Added a new subsection "Extending with Custom Module Entities" under the "Establishing/Creating Relations with Installed ABP Modules' Entities" section
• Documented the module-entity-extension.json configuration file and its location in the .suite folder
• Provided a JSON configuration example showing how to specify custom module DLLs
• Added important notes about solution dependencies and build requirements