Remove extraneous trailing quotation marks in concepts/artifacts docs

[collincchoy]

Description

This PR removes the following extraneous trailing quotation marks from the artifacts documentation page.

Section	Screenshot
Creating link artifacts
Creating Markdown artifacts
Creating table artifacts

Checklist

• This pull request references any related issue by including "closes <link to issue>"
  • If no issue exists and your change is not a small fix, please create an issue first.
• This pull request includes tests or only affects documentation.
• This pull request includes a label categorizing the change e.g. maintenance, fix, feature, enhancement, docs.

For documentation changes:

• This pull request includes redirect settings in netlify.toml for files that are removed or renamed.

For new functions or classes in the Python SDK:

• This pull request includes helpful docstrings.
• If a new Python file was added, this pull request contains a stub page in the Python SDK docs and an entry in mkdocs.yml navigation.

[netlify]

✅ Deploy Preview for prefect-docs-preview ready!

Name	Link
🔨 Latest commit	786dabb
🔍 Latest deploy log	https://app.netlify.com/sites/prefect-docs-preview/deploys/65d63c64a7bd000008e88ebc
😎 Deploy Preview	https://deploy-preview-12040--prefect-docs-preview.netlify.app/concepts/artifacts
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[serinamarie]

ty!