Improve PHP 8.5 subtitle to make it less wordy (#1628)

There's no need for the generic "performance improvements, bug fixes, and general cleanup" since every release has that (and the main title and key features description already mention it being faster and cleaner).

Also made the phrasing less wordy and repetitive.

Author: theodorejb

releases/8.5/languages/en.php

@@ -3,7 +3,7 @@
 return [
     'common_header' => 'PHP 8.5 is a major update of the PHP language, with new features including the URI Extension, Pipe Operator, and support for modifying properties while cloning.',
     'main_title' => 'Smarter, Faster, Built for Tomorrow.',
-    'main_subtitle' => '<p><strong>PHP 8.5 is a major update of the PHP language.</strong> It contains <strong>many new features</strong>, such as the new <strong>URI extension</strong>, support for <strong>modifying properties while cloning</strong>, the <strong>Pipe operator</strong>, performance improvements, bug fixes, and general cleanup.</p>',
+    'main_subtitle' => '<p><strong>PHP 8.5 is a major update of the PHP language</strong>, with new features including the <strong>URI extension</strong>, <strong>Pipe operator</strong>, and support for <strong>modifying properties while cloning</strong>.</p>',
 
     'whats_new' => 'What\'s new in 8.5',
     'upgrade_now' => 'Upgrade to PHP 8.5',