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! :)

[skyace65]

Two things here. One linking to the two issues is excessive. It's helpful for a documentation review since that gives me an easy way to verify information, but as an end user it's not helpful.

Two, the link to the PR should be formatted like the other links on this page. but don't just leave it down here, put it after "instead of the traditional res:// path. " in the beginning of the warning.

[skyace65]

This line as well as line 66 need to be broken up. We don't like endlessly long lines. Technically we have no official hard limit. But when I can see it spilling out onto multiple lines on github that's a problem. Personally I make lines 85 characters long at maximum, but again that's not an official limit. It just needs to be shorter and broken up.