From OpenDCIM Wiki
Adding your Site Contact Info
Often times people in your organization will learn about a tool that you have and try to use it, but once presented with a login screen they may not know how to get access to it, or if they have a problem, who to contact. This is easily remedied by creating a file called sitecontact.html and placing it in the root folder of your openDCIM installation. If that file exists, it will be included in the index.php and login_ldap.php pages.
Example sitecontact.html
<h3>For access to this system, please contact:</h3> <a href="mailto:noc@mycompany.com">The Network Operations Center</a>
You can get fancy if you wish and include logos, images, and pretty much anything that is valid HTML.