[WIP] Translating Tutorial/Part-Four

[mohamedsgap]

Working on translating tutorial/part-four

[asantarissy]

@mohamedsgap what is the status on this?
Also, make sure you pull the master branch to make sure that your edits are up to date.

> git remote add upstream https://github.com/gatsbyjs/gatsby-ar.git
> git checkout doc-tutorial-part-four
> git pull upstream master

[3imed-jaberi]

@mohamedsgap, any update here !!