add known issue about python dependency compile errors in Linux

README.md

 
 ## Known issues
 
-* The Linux Editor 2019.4.7f1 and 2019.4.8f1 might hang when importing HDRP-based Perception projects. For Linux Editor support, use 2019.4.6f1 or 2020.1
+* The Linux Editor 2019.4.7f1 and 2019.4.8f1 might hang when importing HDRP-based Perception projects. For Linux Editor support, use 2019.4.6f1 or 2020.1.
+* When opening the Perception project in Linux Editor, a package dependency on Python will be added and will cause compile errors. This can be fixed by changing the package.json file manually.
 
 ## License
 * [License](com.unity.perception/LICENSE.md)