Add info about config false leafs to describe

Change-Id: Ie256f11617a48ec6dfa913cae1484550e9ec8664
diff --git a/src/yang_schema.cpp b/src/yang_schema.cpp
index 2719bc6..046bfcd 100644
--- a/src/yang_schema.cpp
+++ b/src/yang_schema.cpp
@@ -455,3 +455,8 @@
     auto node = getSchemaNode(path.c_str());
     return node->dsc() ? std::optional{node->dsc()} : std::nullopt;
 }
+
+bool YangSchema::isConfig(const std::string& path) const
+{
+    return getSchemaNode(path.c_str())->flags() & LYS_CONFIG_W;
+}