fix readme

README.md

@@ -1,10 +1,4 @@
-## PM-ART: Durable Linearizable Adaptive Radix Tree
-
-### Branches:
-- master is our correct implementation.
-- no_nvm_mgr allocates nodes in dram and use for some test.
-- nvm_mgr is the development branch that we develop the correct nvm memory management.
-- pmdk_mgr is using pmdk to test other indexes.
+## ROART: Range Optimized Adaptive Radix Tree
 
 ## Build & Run