Add config file for arcanist

This is for the commanline-client to access https://bugs.libssh.org

Signed-off-by: Andreas Schneider <asn@cryptomilk.org>

.arcconfig

@@ -0,0 +1,3 @@
+{
+  "phabricator.uri" : "https://bugs.libssh.org/"
+}