refactor: replace static react title with github username (#32)

This is the only "known" information about the user without performing the GitHub fetch call. Let's put this there for now and implement helmet.

public/index.html

@@ -19,7 +19,7 @@
 			work correctly both with client-side routing and a non-root public URL.
 			Learn how to configure a non-root public URL by running `npm run build`.
 		-->
-		<title>React App</title>
+		<title>%REACT_APP_GITHUB_USERNAME%</title>
 		<style type="text/css">
 			html, body, #root {
 				height: 100%;