Create 9.28.md

doc/9.28/9.28.md

+# 9.28
+
+* 学习插件 MixedRealityToolkit-Unity（[MRTK](https://github.com/Microsoft/MixedRealityToolkit-Unity)）
+
+* [环境安装](https://docs.microsoft.com/zh-cn/windows/mixed-reality/install-the-tools?tabs=unity)
+  * Win 10
+  * VS 2019 16.2及以上版本
+  * Windows 10 SDK (10.0.18362.0)
+  * HoloLens 2 仿真器
+  * [学习博客](https://blog.csdn.net/li1214661543/article/details/107508410?utm_medium=distribute.pc_relevant_t0.none-task-blog-BlogCommendFromMachineLearnPai2-1.nonecase&depth_1-utm_source=distribute.pc_relevant_t0.none-task-blog-BlogCommendFromMachineLearnPai2-1.nonecase)
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