Update ndarray.md

[MwithHeart]

Description

Edited some parts of ndarray.md for easier comprehension, mostly around the introduction part of the page.

Issue Solved

Type of Change

• Fixed a typo.
• Updated the documentation

Checklist

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

[CLAassistant]

All committers have signed the CLA.

[dakshdeepHERE]

The changes looks decent, let's move it to second review.