Update of Meta Matching Models Repository

[ling zijie]

Dear CBIG users, Recently we found that in meta-matching with stacking, not normalizing y (labels) will affect performance. Therefore, we have updated our example code in Meta_matching_models repo for clearer usage guidance. Note that all results from our studies do perform this z-normalization, and they are unaffected by this update to the repository. Feel free to try our updated repo and email the cbig-users mailing list if you have any further issues regarding this update. Thank you! Best regards, Zijie