fix(classic): update docs for security deprecation

[ntindle]

We need to clearly state that the classic AutoGPT is unsupported for security reasons.

Changes 🏗️

Adds a readme for classic autogpt to show that we won't update

Checklist 📋

For code changes:

• I have clearly listed my changes in the PR description
• I have made a test plan
• I have tested my changes according to the test plan:
  • Test Plan

Test Plan

• Open the classic readme and make sure it renders
• Test the links
• Check the docs page for classic has the warning

[qodo-merge-pro]

PR Reviewer Guide 🔍

Here are some key observations to aid the review process:

⏱️ Estimated effort to review: 1 🔵⚪⚪⚪⚪

🧪 No relevant tests

🔒 No security concerns identified

⚡ Recommended focus areas for review Broken Link The documentation link on line 57 contains a space between the text and URL which breaks the markdown link formatting Navigation Issue The getting started instructions tell users to cd into 'classic' directory but this may not exist since the clone command gets the whole repo

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[ntindle]

nodejs/node#55829 related to failure

[kbarnard10]

Suggesting to replace mentions of "AutoGPT" with "AutoGPT Classic" when referring to the original implementation to avoid confusion with the current state of the project (platform and self-hosted), which is actively supported.

[itsababseh]

This looks good to me and is more clear with AutoGPT Classic!