fix document in TFNet related examples (#779)
fix document in TFNet related examples (#779)

* fix document

* fix scripts

yangw1234/BigDL,intel-analytics/BigDL,intel-analytics/BigDL,yangw1234/BigDL,intel-analytics/BigDL,yangw1234/BigDL,intel-analytics/BigDL,yangw1234/BigDL