Add behavior change note for @export_file annotation in Godot 4.4

[Ayush41]

This PR updates the "Upgrading to Godot 4.4" documentation to include a breaking change notice for the @export_file annotation.

As of Godot 4.4, setting a value via the Inspector stores it as a uid:// reference instead of the familiar res:// path. This causes mixed path formats and may break assumptions in GDScript or serialized .tscn/.tres files.

Based on issue #11065

Details

• In 4.4, @export_file behavior changed, and there's no built-in way to retain res:// paths from the Inspector.
• Users must manually edit .tscn or .tres files to preserve the old path style.
• In 4.5, a new annotation @export_file_path was introduced to restore the original behavior explicitly.

This documentation update helps users understand:

• Why their exported paths changed.
• How to work around it in 4.4.
• What to use in 4.5+ to restore the previous behavior.

References

• Fixes: "addons" folder should be renamed to "plugins" godot#11065
• Related PR (4.5): Add @export_file_path to export raw paths (no UID) godot#105414
• UID storage changes: Array of files is saved as uids in ProjectSettings since 4.4 godot#104818

Let me know if this needs formatting changes or should be placed in a different section.

[Calinou]

I would list this as a behavior change in the Core section rather than a breaking change. While it may break things in your project, it won't cause a project with formerly valid API usage to be invalid (this is generally what's understood as a breaking change).

[Ayush41]

@Calinou Just checking in, looking to update or close the PR if it's no longer relevant. Let me know if any changes are needed! :)

[Ayush41]

@Calinou @skyace65 @AThousandShips I've made the requested changes. Let me know if anything else is needed. Looking forward to the merge :)

[Ayush41]

@skyace65 @AThousandShips @Calinou Done Fixing the typo and confirmed everything looks good now to be merged!