add first information about the infodesk

docs/facilities.md

@@ -2,6 +2,18 @@
 
 ## Infodesk
 
+If you have a question about the camp, e.g. where to find what, our job is
+to know, or to find out. Follow us on Mastodon or join our Matrix Channel for
+Announcements!
+
+### How to contact us
+
+* Our Tent: Close to the entrance at the main street. Position/Map TBD
+* DECT: 1111 (Dial-In-Number: TBD)
+* Matrix: TBD
+* IRC: #c3infodesk on hackint.org
+* Mastodon: [@c3infodesk@chaos.social](https://chaos.social/@c3infodesk) (requests via the other channels are preferred).
+
 ## Bars
 
 Fullfill all your cold drink needs.