Add new terms: JSON, NVM, PaaS, SaaS, TONL, UML

[halukerenozlu]

This PR adds six new terms to the Dev Encyclopedia:

• JSON (JavaScript Object Notation): Lightweight data-interchange format that's easy for humans to read and write and easy for machines to parse and generate.
• NVM (Node Version Manager): A tool that allows developers to install and manage multiple Node.js versions on the same system.
• PaaS (Platform as a Service): Cloud computing model providing a platform that allows developers to build, run, and manage applications without dealing with infrastructure complexity.
• SaaS (Software as a Service): Cloud-based software delivery model where applications are hosted by a service provider and accessed via the internet.
• TONL:TONL is a production-ready data platform for LLM.
• UML (Unified Modeling Language): A standardized modeling language used to visualize, design, and document software system architecture and processes.

These additions broaden the encyclopedia with foundational and widely used technical concepts.