Adding upstream version 3.1.0+dfsg.

Signed-off-by: Daniel Baumann <daniel@debian.org>

tests/yanglint/modules/modconfig.yang

@@ -0,0 +1,17 @@
+module modconfig {
+  namespace "urn:yanglint:modconfig";
+  prefix mc;
+
+  container mcc {
+    leaf lft {
+      type string;
+      config true;
+      mandatory true;
+    }
+    leaf lff {
+      type string;
+      config false;
+      mandatory true;
+    }
+  }
+}