Update README.md

Author: marcellszi

README.md

@@ -20,7 +20,7 @@ We provide the following files:
     - See [tabular_demo](notebooks/tabular_demo.ipynb)...
 - `rna3db-jsons.tar.gz` [[Download](https://github.com/marcellszi/rna3db/releases/latest/download/rna3db-jsons.tar.gz)]
     - All [JSON](https://en.wikipedia.org/wiki/JSON) files generated by RNA3DB
-- `rna3db-mmcifs.v2.tar.xz` [[Download](https://github.com/marcellszi/rna3db/releases/download/2024-01-10/rna3db-mmcifs.v2.tar.xz)] (**EXPERIMENTAL**)
+- `rna3db-mmcifs.tar.xz` [[Download](https://github.com/marcellszi/rna3db/releases/latest/download/rna3db-mmcifs.tar.xz)]
     - Hierarchical folders of the training/testing sets containing single-chain [PDBx/mmCIF](https://en.wikipedia.org/wiki/Macromolecular_Crystallographic_Information_File) files 
     - Most convenient for getting started with training and testing using RNA3DB
     - This format is currently experimental. If you find any problems, please [submit an issue](https://github.com/marcellszi/rna3db/issues).