Bump PHP requirement to PHP 7.1 as per core 3.0

Author: Gert-dev

index.html

@@ -313,7 +313,7 @@ <h2 id="what-do-i-need">Awesome! What do I need?</h2>
         </p>
 
         <ul>
-            <li><em>PHP 5.6 or higher</em> &mdash; The code you're actually writing can be anything ranging from PHP 5.2 up to (and including) PHP 7.1.</li>
+            <li><em>PHP 7.1 or higher</em> &mdash; The code you're actually writing can be anything ranging from PHP 5.2 up to (and including) PHP 7.1.</li>
             <li><em>php-sqlite and SQLite >= 3.7.11</em> &mdash; Required as back end for the indexing database.</li>
             <li><em>php-mbstring</em> &mdash; Required as source code can contain Unicode characters in strings or comments.</li>
             <li><em>openssl</em> &mdash; Required to fetch dependencies properly via Composer.</li>