Add how to use PHP Code link to project main page

Please can you add this link to the main page as it shows how to compare one field against another using the PHP Code option.

https://www.drupal.org/node/1537028

This documentation shows how to use the $this variable and from it to reach other fields in the Entity / Node / etc that the "current" field is in.

Very useful examples for comparing the date in the "current" field against a date on one of the other fields.