fix: correct deno install

[xbinaryx]

Prerequisites checklist

• I have read the contributing guidelines.

What changes did you make? (Give an overview)

This pull request incorporates the following changes:

Uses the JSR registry prefix for Deno installation: deno add jsr:@eslint/css
Adds a note indicating that ESLint support in Deno is experimental.

Related Issues

Closes #66

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: xbinaryx (7f2339a)

[MikeMcC399]

@xbinaryx

• There was already an on-going conversation in Bug: Deno install error: @eslint/css is missing a prefix #66 about correcting this issue, so based on that I have submitted a PR docs: add jsr and experimental to Deno command #71 before I noticed that you had also submitted a PR.
• In your commit message, you have used fix:. I have used docs: since the change does not affect any code. See https://www.conventionalcommits.org/en/v1.0.0/#summary for guidance.
• Following general ESLint instructions https://eslint.org/docs/latest/contribute/pull-requests it's a good idea to first indicate that you want to work on a issue before submitting a PR to avoid duplication of effort as has occurred here.

[nzakas]

Merged #71, which solves the same problem.

[xbinaryx]

Hi yea sorry about this. I encountered this issue while using Deno. As there wasn't a pre-existing PR nor was the issue assigned, I took the liberty of implementing the fix. All good though.