use mass as issuer

Author: Crow-Control

public/.well-known/matrix/client

@@ -5,8 +5,8 @@
   "m.identity_server": {
     "base_url": "https://vector.im"
   },
-    "org.matrix.msc2965.authentication": {
-        "issuer": "https://account.trueforge.org/application/o/matrix",
-        "account": "https://mas.trueforge.org/account"
-    }
+  "org.matrix.msc2965.authentication": {
+    "issuer": "https://mas.trueforge.org",
+    "account": "https://mas.trueforge.org/account"
+  }
 }