Add CC-BY-4.0 license

LICENSE

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+Creative Commons Attribution 4.0 International (CC BY 4.0)
+
+Copyright (c) 2026 IDEAS Lab, Northwestern University
+
+You are free to:
+
+  Share — copy and redistribute the material in any medium or format
+  Adapt — remix, transform, and build upon the material
+          for any purpose, even commercially.
+
+Under the following terms:
+
+  Attribution — You must give appropriate credit, provide a link to
+  the license, and indicate if changes were made. You may do so in any
+  reasonable manner, but not in any way that suggests the licensor
+  endorses you or your use.
+
+  No additional restrictions — You may not apply legal terms or
+  technological measures that legally restrict others from doing
+  anything the license permits.
+
+Full license text: https://creativecommons.org/licenses/by/4.0/legalcode
+
+----------------------------------------------------------------------
+
+This license covers the generated artifacts in this dataset: scene
+state JSON files, diagnostics (prompts, goal-condition trees, LTL
+specs), and rollout videos. It does NOT extend to the underlying
+BEHAVIOR-1K scene and object assets, which are referenced by id in
+this dataset but not redistributed here; those assets remain subject
+to their own license terms:
+
+  https://github.com/StanfordVL/BEHAVIOR-1K