Add Cognee to Graph Construction section

[thisisharsh7]

Adding Cognee to the Graph Construction section. Cognee is an open-source platform that automatically constructs knowledge graphs from unstructured data (documents, PDFs, audio, images) using LLMs.

Why Graph Construction category

Cognee belongs in Graph Construction because it:

• Generates knowledge graphs from unstructured data sources
• Extracts entities and relationships automatically using LLM-powered processing
• Complements existing tools like Morph-KGC and Ontop which focus on structured data mapping

thanks!