MAGETWO-48568: CLONE - PHP bug in libxml can bring website down [is r…

…elevant for php versions less than 5.5.22]

- Updated README file

README.md

@@ -33,7 +33,7 @@ Use the following table to verify you have the correct prerequisites to install
 		<td><a href="http://devdocs.magento.com/guides/v2.0/install-gde/prereq/apache.html">Apache</a></td>
 	</tr>
 	<tr>
-		<td>PHP 5.5.x or 5.6.x</td>
+		<td>PHP ~5.5.22 or 5.6.x</td>
 		<td><code>php -v</code></td>
 		<td><a href="http://devdocs.magento.com/guides/v2.0/install-gde/prereq/php-ubuntu.html">PHP Ubuntu</a><br><a href="http://devdocs.magento.com/guides/v2.0/install-gde/prereq/php-centos.html">PHP CentOS</a></td>
 	</tr>