Update comment on Python3Core

Author: eregon

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/Python3Core.java

@@ -395,9 +395,7 @@
 import com.oracle.truffle.api.strings.TruffleString;
 
 /**
- * The core is intended to the immutable part of the interpreter, including most modules and most
- * types. The core is embedded, using inheritance, into {@link PythonContext} to avoid indirection
- * through an extra field in the context.
+ * The core is a historical artifact and PythonContext and Python3Core should be merged.
  */
 public abstract class Python3Core {
     private static final int REC_LIM = 1000;