PFM: add known issues (Xilinx#104)

Author: imrickysu

Vitis_Platform_Creation/Introduction/02-Edge-AI-ZCU104/step4.md

@@ -21,6 +21,7 @@
   - [Test 3: Run a Vitis-AI Demo](#test-3-run-a-vitis-ai-demo)
     - [Create the design](#create-the-design)
     - [Run Application on Board](#run-application-on-board)
+    - [Known Issues](#known-issues)
   - [Congratulations](#congratulations)
 
 ## Step 4: Test the Platform
@@ -473,6 +474,11 @@ This test will run a Vitis-AI test application in DPU-TRD to verify DPU function
 
 </details>
 
+#### Known Issues
+
+1. The default setting of PMIC (irps5401) on ZCU104 can't afford DPU running on heavy loading. You may see crash or hang on heavy loading.
+   - Please refer to [DPU TRD Known issues](https://github.com/Xilinx/Vitis-AI/blob/master/dsa/DPU-TRD/prj/Vitis/README.md#553-known-issues) for more information. (Ref: [issue 101](https://github.com/Xilinx/Vitis-Tutorials/issues/101))
+
 ### Congratulations
 
 We have completed creating a custom platform from scratch and verifying it with a simple vadd application and a relatively complex Vitis-AI use cases.