docs: add IoT setup guide for new developers

[Essaba2020]

Problem
The current documentation does not include a clear setup guide
for the IoT layer, making it difficult for new developers to
configure and deploy the IoT components of the system.

Proposed Solution
Add a dedicated IoT setup guide inside the docs folder that
explains how to configure the IoT layer, connect sensors,
and run the Flask ingestion server locally.

Expected Benefit
This will help new contributors quickly understand and set up
the IoT components, improving onboarding and reducing setup errors.