chore(docs): Update outdated building a theme tutorial snippets (#35792)
chore(docs): Update outdated building a theme tutorial snippets (#35792)

Fixing #35784

Signed-off-by: Josh Cox <c028c213ed5efcf30c3f4fc7361dbde0c893c5b7@webhosting.coop>
gatsbyjs/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby