www/php-concrete-cms: add package version 9.2.6

Concrete CMS is successor of www/php-concrete5.

Concrete CMS

Concrete CMS is a web content management system designed for creating and
managing websites.  Its interface is user-friendly, catering to both novices
and experts.

Concrete is written in PHP and JavaScript and it pulls data from a MySQL
database.

In Concrete CMS, your website is structured as a hierarchy of pages
organized within a sitemap.  Each page adheres to a specific Page Type and
utilizes one of its associated Templates.  These Templates are PHP files
that combine standard HTML/CSS with dynamic Block Areas.  Within Block
Areas, you can insert Blocks, which range from basic HTML Text to advanced
interactive features like forms.  Block Areas can be further refined using
Layouts or Containers.  While Layouts simply split a block area into
columns, Containers are code-defined and can encompass additional markup and
styling.

* Files
* Users, Groups & Authentication
* Permissions & Workflow
* Attributes
* Packages

(taca)