Add new entry on virtual machines

[YanisaHS]

Description

I added the virtual-machines concept and virtual-machines.md file inside. The file (1) introduces VMs, (2) explains how VMs work, (3) lists the benefits of using VMs, and (4) notes who uses VMs.

Closes #710

Type of Change

• Adding a new entry

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] Under "Development" on the right, I have linked any issues that are relevant to this PR (write "Closes # in the "Description" above).

[YanisaHS]

@Dusch4593 Thanks for your detailed feedback!! Done 🥳

[YanisaHS]

@Dusch4593 Done! 😄

[YanisaHS]

@SSwiniarski Thanks for the review! Just committed those changes 🥳

[YanisaHS]

@Dusch4593 Done! 🥳

[Dusch4593]

@SSwiniarski Anything left to add, change, or check before we merge?

[YanisaHS]

@Dusch4593 Would it be possible to add the hacktoberfest tag to this PR? Not sure how it works, but trying to do that thing 🥳 I think this one isn’t showing up in my account because it doesn’t have the tag.

[Dusch4593]

@Dusch4593 Would it be possible to add the hacktoberfest tag to this PR? Not sure how it works, but trying to do that thing 🥳 I think this one isn’t showing up in my account because it doesn’t have the tag.

I can certainly add the tag, though I'm not 100% certain it would be counted because the PR was created prior to Oct. 1st. (source)