Added file on index_select

[Neema-Joju]

Description

Added a new entry file on .index_select(). Improving documentation and providing more context for the users to understand.

Issue Solved

Closes #5629

Type of Change

• Adding a new entry
• Updating 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.

[SaviDahegaonkar]

Hey @Neema-Joju ,
The entry is nicely written. I have suggested a few changes for this entry. Please make them as soon as possible.

Thanks,
Savi

[SaviDahegaonkar]

Suggested change

	tensor([[1, 2, 3, -8],
	[-1, 7, 6, 3]])
	tensor([[1, 4, -1, 5],
	[3, 8, 6, 9]])
	tensor([[1, 2, 3, -8],
	[-1, 7, 6, 3]])
	tensor([[1, 4, -1, 5],
	[3, 8, 6, 9]])

This output incorrectly selects values from rows instead of columns, which is incorrect, so please correct the way of printing this output.

[Neema-Joju]

The first tensor r does select values from the rows not columns.