Docs: Explain shallow copy behavior for slice method

[kartikeymishra2202]

##The Problem:Question-5.
The current documentation for Array.prototype.slice() is correct but incomplete. It omits the crucial detail that it performs a shallow copy. This can be misleading and lead to hard-to-debug issues when developers work with arrays of objects, as the original array's nested objects can be unintentionally mutated.

The Solution

This PR addresses this gap by making the behavior explicit and providing a clear example. The changes include:

Adding a new subsection, "A Note on Shallow Copying", to the slice() documentation.

Clearly explaining that slice() copies references to nested objects, not the objects themselves.

Providing a concise code example that demonstrates this effect.

Updating the slice vs. splice comparison table to reflect this important detail for quick reference.

The Benefit

This clarification will help developers avoid common pitfalls and prevent unintentional mutations. It makes the documentation more robust and helpful, especially for those who are new to this concept.