Remove screenshot column

[adhilto]

🗣 Description

Removed the screenshot column from the setup testbed instructions.

💭 Motivation and context

The images were all resulting in 404 errors and the instructions are clear enough without them.

🧪 Testing

N/A

📷 Screenshots (if appropriate)

✅ Pre-approval checklist

• This PR has an informative and human-readable title.
• Changes are limited to a single goal - eschew scope creep!
• All future TODOs are captured in issues, which are referenced
  in code comments.
• All relevant type-of-change labels have been added.
• These code changes follow cisagov code standards.
• All relevant repo and/or project documentation has been updated
  to reflect the changes in this PR.
• Tests have been added and/or modified to cover the changes in this PR.
• All new and existing tests pass.

✅ Pre-merge checklist

• Revert dependencies to default branches.
• Finalize version.

✅ Post-merge checklist

• Create a release.

[rgbrow1949]

Piece of cake, Approved.

[mreeve-snl]

https://github.com/cisagov/LME/tree/patch-testbed-instructions/testing
fixed it :)
I'll approve, and let one of you merge it

[mreeve-snl]

LGTM