Change some Japansese expressions to better ones. (#307)
Change some Japansese expressions to better ones. (#307)

* Replace "貢献者" to "コントリビューター" in Japanese document

https://help.github.com/ja/articles/viewing-a-projects-contributors

* Replace "懸念事項" to "Issue" in Japanese document

https://help.github.com/ja/articles/about-issue-and-pull-request-templates

* Replace "人間に優しい" to "ヒューマンフレンドリーな" in Japanese document

https://ci.nii.ac.jp/naid/110004788357

olivierlacan/keep-a-changelog,olivierlacan/keep-a-changelog