docs: add arrays documentation in C

[Srishti-Gupta74]

Related Issue

Fixes #13

---

Description

Added structured and beginner-friendly documentation for Arrays in C.

Included

• Introduction to arrays
• Syntax and initialization
• Accessing array elements
• Input/output examples
• Advantages and disadvantages
• Time complexity analysis
• Applications of arrays
• Basic interview questions
• Practice problems

This PR focuses only on the Arrays topic for easier review and maintainability.

---

Type of Change

• Bug fix
• New feature
• Documentation update
• UI/UX improvement
• Refactor

---

Screenshots / Demo

Documentation preview added successfully in markdown format.

---

How Has This Been Tested?

• Verified markdown formatting locally
• Checked folder structure consistency
• Reviewed rendered documentation preview on GitHub

---

Checklist

• My code follows the project structure and conventions
• I have tested the changes locally
• I have linked the related issue properly
• I have added screenshots where applicable
• No existing functionality was broken

---

AI Usage

• I have not used AI tools for this contribution

• I have used AI tools (ChatGPT, Copilot, Claude, etc) and I have reviewed, verified, and understood all generated code/content before submitting this PR

If AI tools were used, briefly explain how:

Used AI assistance for drafting and organizing beginner-friendly documentation content. All content was reviewed and verified before submission.

---

Additional Notes

This PR adds the initial DSA documentation structure under notes/dsa/arrays for future topic-wise contributions.

[vercel]

Someone is attempting to deploy a commit to the PushkarScripts Team on Vercel.

A member of the Team first needs to authorize it.

[pushkarscripts]

Few problems with this PR:

• Follow the file structure of the project.
  i.e., Instead of notes/dsa/array/README.md, use the app/sem#/[subject-name]/ format.
• Update the necessary files like: apps/components/subjects.tsx
• Replace Fixes # with Related to # as there's more than one PR for this issue.

Make these changes and update the PR