update Release notes of r0.6

RELEASE.md

+# Release 0.6.0-beta
+## Major Features and Imporvements
+* AutoPoly refactor to support integrating multi-backend targets easily
+  * Employ a pass/passmgr framework to manage all the transformations of ISL schedule tree in which transformation such as InitialSchTree and tileOuterBand would be considered as a pass to schedule tree.
+  * Refactor some data structure of poly so that they can de-couple with Davinci chips.
+* Backend refactoring
+  * Enhance min alignment analysis with more accurate propagate conditions.
+  * Finetune pragma using alignment information before EmitInsn pass.
+  * Simplify EmitInsn pass by unifying the emit method for different patterns.
+* change the way of using TVM
+  * Delete the repository ktvm and reference TVM directly in sourcecode(third_party/incubator-tvm).
+  * bring back the code which support GPU operator generation.
+
+## Bugfixes
+* fix wrong hoist problem in multicore loop switch hoist pass(!87).
+* fix scalar rearrange bug(!84).
+* fix matmul tuning and support all space tuning(!73).
+* fix variable broadcast_idx redefinition error when pragma dma_copy is replaced by opt_broadcast(!45).
+* fix the bug in broadcast_rewrite(!22).
+* fix bugs of multi-core processing(!33).
+* fix a bug that extra pipe_barrier inserted in the loop(!30).
+* fix inefficient auto tiling for axis with tail and remove duplicated check(!6).
+
+## Contributors
+Thanks goes to these wonderful people:
+brovensmile, chengyun, chenlei_autodiff, chengbin, ConnZhai, fuxiaoteng, gaoxiong, gengzhen, hanhuifeng, KasonChan, luoyin, lvwenyuan, peiwenfang, xuhui, yangsijia, wangzhuo325, wYann
+
+Contributions of any kind are welcome!
+
+# Release 0.5.0-beta
+## Major Features
+* Support auto-schedule and code-generation on Ascend platform.
+* Provide C++ APIs of basic operators used in MindSpore.
+* Support Elementwise-Elementwise, Reduce-Elementwise fusion patterns in Bert.
+* Support LambUpdateWithLR, LambNextMv, BatchMatmul optimazition for Bert.
+
 ## Initial Version
-- Upload the initial framework
-- Basic support for Ascend910 platform
-- Integration with GraphKernel
+* Upload the initial framework
+* Basic support for Ascend910 platform
+* Integration with GraphKernel