docs(readme): Start adding documentation for React version

docs/latest/_book/history/v1/gitbook/gitbook-plugin-github/plugin.js

@@ -0,0 +1,14 @@
+require([ 'gitbook' ], function (gitbook) {
+    gitbook.events.bind('start', function (e, config) {
+        var githubURL = config.github.url;
+
+        gitbook.toolbar.createButton({
+            icon: 'fa fa-github',
+            label: 'GitHub',
+            position: 'right',
+            onClick: function() {
+                window.open(githubURL)
+            }
+        });
+    });
+});