docs: Avoid identifier has already been declared error

Author: jcs090218

docs/static/main.js

@@ -1,13 +1,13 @@
-
-const quote = "Learn once, run anywhere";
-
 window.addEventListener('load', function () {
   var subtitle = document.getElementsByClassName("_subtitle");
 
   // In case adding more than once!
   if (subtitle.length != 0)
     return;
 
+  // Place it here to avoid error: `Identifier 'xxx' has already been declared`.
+  const quote = "Learn once, run anywhere";
+
   const titles = document.getElementsByClassName("gdoc-brand__title");
 
   const title = titles[0]