specify known issue

Author: elneruda

README.md

@@ -37,6 +37,12 @@ github "teads/TeadsSDK-iOS" "4.8.0"
 
 Integration instructions are available on [Teads SDK Documentation](https://support.teads.tv/support/solutions/articles/36000165909).
 
+## Known Issue
+
+### Xcode 12 Excluded Architecture
+
+[#142](https://github.com/teads/TeadsSDK-iOS/issues/142) Our third party viewability solution is unfortunately not yet compatible with ARM Simulator Architecture.
+
 ## Changelog
 
 See [changelog here](CHANGELOG.md).