[usecase-cordova] Add README.md for cordova usecase
[wrt-usecase] Add readme files to subcase
Merge pull request #983 from wanghongjuan/wanghongjuan/usecase/readme

[wrt-usecase] Add readme files to subcase
Merge pull request #982 from haoxli/haoxli/usecase/cordova-readme

[usecase-cordova] Add README.md for cordova usecase