fix(docs): remove Appsody documentation and sidebar reference

[KauanAfonso]

Description

This PR removes the deprecated Appsody documentation and its reference from the sidebar navigation.

Appsody is no longer actively maintained, and the documentation is outdated. This cleanup removes:

• The Appsody documentation file (docs/site/Appsody-LoopBack.md) - already deleted
• The sidebar reference to the Appsody documentation page

Checklist

• DCO (Developer Certificate of Origin) signed in all commits
• npm test passes on your machine
• New tests added or existing tests modified to cover all changes
• Code conforms with the style guide
• API Documentation in code was updated
• Documentation in /docs/site was updated
• Affected artifact templates in packages/cli were updated
• Affected example projects in examples/* were updated

Notes

• This is a documentation-only change, no code changes required
• No tests needed as this only removes documentation
• No API changes
• No template or example updates needed

[KauanAfonso]

I am trying to solve this ubuntu error from CI/CD in the other PR.
The issue also occurs in the most recent commits that were merged into the master branch.
Pull request link: #11642

[dhmlau]

@KauanAfonso, thanks for cleaning up the docs.

[dhmlau]

@KauanAfonso, thanks for your contribution! Your PR has been merged! 🎉