feat(Unity): Added WebGL limitations (#13637)

Author: bitsandfoxes

docs/platforms/unity/troubleshooting/known-limitations.mdx

@@ -44,3 +44,20 @@ This is also why you might end up with very high line numbers (in the several th
 ## Cysharp
 
 Currently, the SDK fails to provide line numbers and source context in combination with Cysharp. For context, the SDK relies on Unity's IL2CPP backend to provide it with instruction addresses for Sentry generate line numbers in events. When using Cysharp, those instruction addresses default back to `0x0` once the stacktrace goes into the library. There is no known workaround for this.
+
+## WebGL Support
+
+When targeting WebGL, you have the option of setting the `PlayerSettings.WebGL.exceptionSupport`, but be mindful of the following limitations:
+
+- Setting it to `WebGLExceptionSupport.None` is not supported by the SDK.
+- For the SDK to be able provide stack traces, the support needs to be set to `WebGLExceptionSupport.FullWithStacktrace`.
+- The SDK is currently not able to provide line numbers due to the IL2CPP backend not being available.
+
+## Managed Stripping Level
+
+When building with Unity 2019, the `ManagedStrippingLevel` needs to be set to `ManagedStrippingLevel.Low`. Otherwise, the build will fail throwing the following error:
+
+```
+Fatal error in Unity CIL Linker
+System.ArgumentException: Member 'System.Void System.Runtime.CompilerServices.NullableAttribute::.ctor(System.Byte)' is declared in another module and needs to be imported
+```