Added inline comment.

gatsby-node.js

@@ -124,6 +124,9 @@ exports.createPages = async ({graphql, boundActionCreators}) => {
             process.exit(1);
           }
 
+          // A leading "/" is required for redirects to work,
+          // But multiple leading "/" will break redirects.
+          // For more context see github.com/reactjs/reactjs.org/pull/194
           const toPath = slug.startsWith('/') ? slug : `/${slug}`
 
           redirectToSlugMap[fromPath] = slug;