Update PHP page claims WordPress does support 5.2

[websupporter]

On the page about updating PHP it states:

WordPress itself works with PHP versions as far back as 5.2.4 (we’re currently recommending version 7.3, so this is great backward compatibility!),

​https://wordpress.org/support/update-php/

As of today (release of WordPress 5.2) this seems no longer true :)

[dd32]

These versions are controlled by https://meta.trac.wordpress.org/browser/sites/trunk/wordpress.org/public_html/wp-content/mu-plugins/pub/servehappy-config.php

[SergeyBiryukov]

In 8742:

API: ServeHappy: Bump the minimum required PHP version to 5.6.20, to match the version bump in WordPress 5.2.

Props websupporter.
Fixes #4443. See ​#WP46594.