Update readme

README.md

@@ -378,10 +378,11 @@ vm2 ./script.js
 
 ## Known Issues
 
-* It is not possible to define a class that extends a proxied class.
+* It is not possible to define a class that extends a proxied class. This includes using a proxied class in `Object.create`.
 * Direct eval does not work.
 * Logging sandbox arrays will repeat the array part in the properties.
 * Source code transformations can result a different source string for a function.
+* There are ways to crash the node process from inside the sandbox.
 
 ## Deployment