Contribute NoSQL Database section and a MongoDB + PHP

[Pash10g]

This PR adds an introductory guide to NoSQL databases, emphasizing MongoDB and its integration with PHP. The guide is structured in Markdown format and aims to provide a comprehensive overview for developers who are new to NoSQL databases and MongoDB.

Changes

Introduction to NoSQL Databases:

Provides an overview of NoSQL databases and their categories, including Document Databases, Key-Value Stores, Column-Oriented Databases, and Graph Databases.
MongoDB Overview:

Highlights MongoDB as a leading NoSQL database, describing its document model, scalability, aggregation framework, and performance.
Discusses MongoDB's support for multiple data models, including key-value, graph, and time-series data.

MongoDB and PHP Integration:

Details the steps to install the MongoDB PHP driver.
Provides sample PHP code to demonstrate connecting to a MongoDB database, inserting a document, and querying a document.

[Pash10g]

Hello @codeguy @petk and @Xymph ,

I am reaching out to get your help on merging this PR.

My name is Pavel and I am developer advocate for Mongo. I've added MongoDB content that we think is useful for PHP community , can you help us merge this PR?

Thanks!

[petk]

Hello, thanks for contributing here. I don't have write access to this repository. I only contribute via PRs here so I won't be able to help you out but @Xymph might I think.

Overall the text is nice addition. 👍

[Xymph]

I was appointed collaborator just so I could merge my own simple fixes, and I have also handled similar PRs by others. But this is not my repo and I'm not so familiar with the overall vision for it, so I'm shying away from more elaborate changes - those are on codeguy's plate.