Readme: Update recommended PHP version to 7.2.

Merge of [42358] to the 4.9 branch.

Props otto42, johnbillion, rachelbaker, jorbin.
Fixes #42789.
Built from https://develop.svn.wordpress.org/branches/4.9@42847


git-svn-id: http://core.svn.wordpress.org/branches/4.9@42677 1a063a9b-81f0-0310-95a4-ce76da25c4cd

readme.html

@@ -58,7 +58,7 @@
 
 <h3>Recommendations</h3>
 <ul>
-	<li><a href="https://secure.php.net/">PHP</a> version <strong>7</strong> or higher.</li>
+	<li><a href="https://secure.php.net/">PHP</a> version <strong>7.2</strong> or higher.</li>
 	<li><a href="https://www.mysql.com/">MySQL</a> version <strong>5.6</strong> or higher.</li>
 	<li>The <a href="https://httpd.apache.org/docs/2.2/mod/mod_rewrite.html">mod_rewrite</a> Apache module.</li>
 	<li><a href="https://wordpress.org/news/2016/12/moving-toward-ssl/">HTTPS</a> support.</li>

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.9.5-alpha-42846';
+$wp_version = '4.9.5-alpha-42847';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.