Update index.md (#157)

Re-arrange the category.

Author: RussellHu41

source/papers/index.md

@@ -4,7 +4,7 @@ title: Publications citing DeepModeling's work
 
 ## Classified by Project (in progress)
 
+- [ABACUS](ABACUS/)
 - [DeePMD-kit](deepmd-kit/)
 - [DP-GEN](dpgen/)
 - [Uni-Mol](uni-mol/)
-- [ABACUS](ABACUS/)