chore(starters): add gatsby-starter-julia (#12797)
chore(starters): add gatsby-starter-julia (#12797)

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## Description
I started with Gatsby a couple weeks ago and redesigned my website with it. I then had the idea to also create it as a starter guide for people who want a minimal blog. So here is my PR with the starter. I hope you like it.

ChristopherBiscardi/gatsby,ChristopherBiscardi/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby,ChristopherBiscardi/gatsby,gatsbyjs/gatsby,ChristopherBiscardi/gatsby,gatsbyjs/gatsby