Document real-time configuration syncing

[mintlify]

Summary

The web editor now syncs configuration changes (branding, colors, header, footer, analytics, etc.) in real-time across collaborators editing the same branch. This PR updates the editor documentation to reflect this capability.

Changes

• editor/configurations.mdx: Added note that configuration changes sync in real-time with other editors on the same branch.
• editor/collaborate.mdx: Added "Real-time editing" section explaining that page content, navigation, and configuration changes sync automatically across collaborators.

Triggered by

Support for real-time collaborative editing of site configuration in the web editor, so multiple team members can update settings simultaneously without conflicts.

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Note

Low Risk
Low risk documentation-only updates that describe new real-time collaboration behavior; no runtime code paths are changed.

Overview
Documents real-time collaboration in the web editor.

Adds a new Real-time editing section to editor/collaborate.mdx and updates editor/configurations.mdx to note that configuration changes sync live across collaborators on the same branch.

^{Written by Cursor Bugbot for commit e1c66e9. This will update automatically on new commits. Configure here.}

[prodev1000]

Reviewed: docs-only change is consistent with the shipped real-time sync behavior for collaborative editor configuration changes.