Update site-constants (#2391)

At the time of writing, the latest version of react is v16.10.1

Author: murdochd

src/site-constants.js

@@ -8,7 +8,7 @@
 // NOTE: We can't just use `location.toString()` because when we are rendering
 // the SSR part in node.js we won't have a proper location.
 const urlRoot = 'https://reactjs.org';
-const version = '16.10.0';
+const version = '16.10.1';
 const babelURL = 'https://unpkg.com/[email protected]/babel.min.js';
 
 export {babelURL, urlRoot, version};