add version for --mutation feature

Author: bqminh

doc/AliSim.md

@@ -558,7 +558,8 @@ This example simulates a new alignment under the Juke-Cantor model from the inpu
 
 Pre-define mutations
 ----------------------------
-AliSim allows users to enfore pre-defined mutations that must occur at some specific nodes of the tree. Those mutations could be, for example, generated by running [VGsim](https://github.com/genomics-HSE/vgsim) with the option `-writeMutations`.
+
+Starting from IQ-TREE v2.2.3, AliSim allows users to enfore pre-defined mutations that must occur at some specific nodes of the tree. Those mutations could be, for example, generated by running [VGsim](https://github.com/genomics-HSE/vgsim) with the option `-writeMutations`.
 
 
 Given a tree file `tree_example.nwk`