Finish issue 15-7 Translation
Fix 25-7 image link
Fix type issue
Merge pull request #237 from oa414/15-7-oa414

完成15-7翻译
finish issue15-5-ryan
Review 15-7
Change file name
Merge pull request #238 from tangren03/new/issue-15-5-ryan

finish issue15-5-ryan
fix issue 15-7
Merge pull request #239 from objccn/review/15-7-onevcat

Review/15 7 onevcat
publish 15-7
Merge remote-tracking branch 'upstream/master'