Fix typo.
translation proposal
Merge pull request #1 from tekapo/patch-1

Fix typo.
Merge pull request #2 from tekapo/patch-2

translation proposal
Update CONTRIBUTING-ja.md

翻訳協力追加
Merge remote-tracking branch 'upstream/ja'

* upstream/ja:
  Update CONTRIBUTING-ja.md
  translation proposal
  Fix typo.