Update README.md

[davin111]

Related Issue: #97 This PR will resolve #97 issue.

Major changes

I wrote README.md about how to run and test our service.

Checklist

This pull request...

• [x] has preceding issues related with it (if resolves some issues, metions them with 'resolve')
• [x] doesn't include too many changes (you should focus on the specific feature in a PR)
• [x] elaborately explains what feature is added, which part is fixed or improved
• [x] has step by step instructions for collaborators, if needed
• [x] has attached screenshots, if appropriate

My codes...

• [x] include enough tests for added and changed parts
• [x] pass all the new and existing tests
• [x] include appropriate comments
• [x] don't introduce unnecessary warnings

[abcthing]

APIDoc가 ReadMe에 있어도 좋을 것 같네요

[davin111]

APIDoc가 ReadMe에 있어도 좋을 것 같네요

@abcthing I reflected it!