Fix typo in Netlify CMS tutorial
Fix typo in Netlify CMS tutorial

Signed-off-by: Thomas KUNTZ <0eee6576d1a5055d188191800f8eec57f1a56e6c@protonmail.com>

gatsbyjs/gatsby,mingaldrichgan/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby,ChristopherBiscardi/gatsby,fk/gatsby,ChristopherBiscardi/gatsby,ChristopherBiscardi/gatsby,ChristopherBiscardi/gatsby,mingaldrichgan/gatsby,gatsbyjs/gatsby,mingaldrichgan/gatsby,fk/gatsby,0x80/gatsby,0x80/gatsby,fk/gatsby,0x80/gatsby