Add a Known Issues file in the Third Party folder (#434)

Signed-off-by: Gaurav Aggarwal <aggarg@amazon.com>
diff --git a/portable/ThirdParty/KnownIssues.md b/portable/ThirdParty/KnownIssues.md
new file mode 100644
index 0000000..593a411
--- /dev/null
+++ b/portable/ThirdParty/KnownIssues.md
@@ -0,0 +1,7 @@
+# Known Issues
+This document lists the known issues in various FreeRTOS third
+party ports.
+
+## ThirdParty/GCC/ARC_EM_HS
+* [Memory Read Protection Violation from Secure MPU on exit from
+interrupt](https://github.com/FreeRTOS/FreeRTOS-Kernel/issues/331)