Update utility.py

Added other image formats that are already verified by imghdr.
Not sure about "pgm" format?

更正链接指向

pick fix nrtr export inference model from drgraph to release/2.3

update cpp infer docs in Release/2.3

 Fix docs

Fix docs

disable glog info

Fixing typos/docs

Fix a serious doc issue

fix load model

update 21-9-15