update machine_reading_comprehension _ce.py

fluid/PaddleNLP/machine_reading_comprehension/_ce.py

@@ -3,6 +3,7 @@
 import os
 import sys
 #sys.path.insert(0, os.environ['ceroot'])
+sys.path.append(os.environ['ceroot'])
 from kpi import CostKpi, DurationKpi, AccKpi
 
 #### NOTE kpi.py should shared in models in some way!!!!