Add sgd docs

[pratik305]

Description

This pull request introduces a new documentation file on Stochastic Gradient Descent (SGD) in the stochastic-gradient-descent.md file. SGD is a widely used optimization algorithm in machine learning and deep learning due to its efficiency and scalability, particularly for large datasets. However, its effectiveness and stability can be significantly influenced by how it is implemented and tuned. This new documentation aims to offer clear, comprehensive insights into SGD’s operation, benefits, and limitations, helping users to better understand and apply this algorithm in their projects.

Issue Solved

Closes #4527

Type of Change

• [x] Adding a new entry
• Editing an existing entry (fixing a typo, bug, issues, etc)
• Updating the documentation

Checklist

• [x] All writings are my own.
• [x] My entry follows the Codecademy Docs style guide.
• [x] My changes generate no new warnings.
• [x] I have performed a self-review of my own writing and code.
• [x] I have checked my entry and corrected any misspellings.
• [x] I have made corresponding changes to the documentation if needed.
• [x] I have confirmed my changes are not being pushed from my forked main branch.
• [x] I have confirmed that I'm pushing from a new branch named after the changes I'm making.
• [x] I have linked any issues that are relevant to this PR in the Issues Solved section.