docs: Add mayan-edms to the showcase

docs/content/showcase/mayan-edms.md

@@ -0,0 +1,14 @@
+---
+date: 2016-06-13T19:38:56-04:00
+description: "Free Open Source Document Management System"
+license: "Apache 2.0"
+licenseLink: ""
+sitelink: http://www.mayan-edms.com/
+sourceLink: https://gitlab.com/mayan-edms/website
+tags:
+- paperless
+- floss
+thumbnail: /img/mayan-edms-tn.png
+title: Mayan EDMS
+---
+