Add open source standard

[davidsetyanugraha]

Fixes #5

Proposed Changes

• [x] Add code of code of conduct (see CODE_OF_CONDUCT.md file). I am proposing the usage of Contributor Covenant. Why? this code of conduct has already been adopted by over 200,000 open source projects (such as React, Tensorflow, Salesforce OSS, Golang, etc).
• [x] Add badges to readme.
• [x] Add issue templates md file. See this github doc.
• [x] Add pull request template md file. See this github doc.
• [x] Enable reported content for the repository. see https://docs.github.com/en/free-pro-team@latest/github/building-a-strong-community/managing-how-contributors-report-abuse-in-your-organizations-repository

[davidsetyanugraha]

@gentaiscool when you get a chance, please kindly check the changes. Thanks.

[davidsetyanugraha]

Need someone with admin access to enable this setting: https://docs.github.com/en/free-pro-team@latest/github/building-a-strong-community/managing-how-contributors-report-abuse-in-your-organizations-repository

[gentaiscool]

Need someone with admin access to enable this setting: https://docs.github.com/en/free-pro-team@latest/github/building-a-strong-community/managing-how-contributors-report-abuse-in-your-organizations-repository

done. The commits look ok.