cann: update the docs CANN.md

Author: shibizhao

docs/backend/CANN.md

@@ -259,10 +259,6 @@ cmake --build build --config release
 Please add the **[CANN]** prefix/tag in issues/PRs titles to help the CANN-team check/address them without delay.
 
 ### Basic Flash Attention Support
-The basic FA kernel with aclnnops has been added in aclnn_ops.cpp.
-
-Authors: Bizhao Shi ([email protected]), Yuxin Yang ([email protected]), Ruiyang Ma ([email protected]), and Guojie Luo ([email protected]).
-
-
-## TODO
-- Support more models and data types.
+The basic FA kernel with aclnnops has been added in aclnn_ops.cpp. 
+Currently, the FA only supports the cases with FP16 KV tensors and NO logit softcap. 
+Since the aclnn interface for flash attention cannot support the logit softcap, we will only update the