Corrected typo.
Merge pull request #225 from hiroakit/dev

Corrected typo.

CLA received and on file - thank you very much !

PS: i have taken a pass over the week-end at re-organizing the directory structure of the documentation but it's not quite there yet... if you want to get started on translation, i would suggest forking the repo and the following directory: documentation/ja_JP where you can start putting translated copies of the rst files.