app/matrix change displayname rules for matrix.0x3c.pl

prefer username as those are more commonly used in this community

Change-Id: Ia9e5394cd672d3f759e89e4b72dc16a5059857b4
diff --git a/app/matrix/matrix.0x3c.pl.jsonnet b/app/matrix/matrix.0x3c.pl.jsonnet
index 4adceb6..ddfccba 100644
--- a/app/matrix/matrix.0x3c.pl.jsonnet
+++ b/app/matrix/matrix.0x3c.pl.jsonnet
@@ -63,6 +63,12 @@
                             "@not7cd:0x3c.pl": "admin", // propabbly
                             "@q3k:0x3c.pl": "admin",
                         },
+                        displayname_template: "{displayname}[T]",
+                        displayname_preference: [
+                            "username",
+                            "full name",
+                            "phone number",
+                        ],
                     },
                 },
             },