replace "ECMAScript 5" with "ES5" in documentation

Author: michaelficarra

index.html

@@ -2577,10 +2577,10 @@ <h2 id="changelog">Change Log</h2>
         representing default options.
         Added an <tt>_.once</tt> function, for manufacturing functions that should
         only ever execute a single time.
-        <tt>_.bind</tt> now delegates to the native ECMAScript 5 version,
+        <tt>_.bind</tt> now delegates to the native ES5 version,
         where available.
         <tt>_.keys</tt> now throws an error when used on non-Object values, as in
-        ECMAScript 5.
+        ES5.
         Fixed a bug with <tt>_.keys</tt> when used over sparse arrays.
       </p>
 
@@ -2628,7 +2628,7 @@ <h2 id="changelog">Change Log</h2>
       <p id="1.1.0">
         <b class="header">1.1.0</b> &mdash; <small><i>August 18, 2010</i></small> &mdash; <a href="https://github.com/jashkenas/underscore/compare/1.0.4...1.1.0">Diff</a> &mdash; <a href="https://cdn.rawgit.com/jashkenas/underscore/1.1.0/index.html">Docs</a><br />
         The method signature of <tt>_.reduce</tt> has been changed to match
-        the ECMAScript 5 signature, instead of the Ruby/Prototype.js version.
+        the ES5 signature, instead of the Ruby/Prototype.js version.
         This is a backwards-incompatible change. <tt>_.template</tt> may now be
         called with no arguments, and preserves whitespace. <tt>_.contains</tt>
         is a new alias for <tt>_.include</tt>.
@@ -2675,7 +2675,7 @@ <h2 id="changelog">Change Log</h2>
         safer duck-typing on collection functions, and cleaner internals. A new
         <tt>_.mixin</tt> method that allows you to extend Underscore with utility
         functions of your own. Added <tt>_.times</tt>, which works the same as in
-        Ruby or Prototype.js. Native support for ECMAScript 5's <tt>Array.isArray</tt>,
+        Ruby or Prototype.js. Native support for ES5's <tt>Array.isArray</tt>,
         and <tt>Object.keys</tt>.
       </p>