apps: resnet18: Add README for development

Signed-off-by: xychen <xychen@listenai.com>
1 job 于fix/resnet18 in 1 minute 和 45 second
latest
状态 作业 ID 名称 覆盖率
  Ztest
已通过 #60865
zgsz-03 generic
ztest_build_only

00:01:45