Add node-info getters to Schema

Change-Id: Iffea96cdcf20763286db19b0ee2b92dbf7c69b6c
diff --git a/src/yang_schema.hpp b/src/yang_schema.hpp
index ea204e2..8471bea 100644
--- a/src/yang_schema.hpp
+++ b/src/yang_schema.hpp
@@ -43,6 +43,8 @@
     const std::set<std::string> enumValues(const schemaPath_& location, const ModuleNodePair& node) const override;
     std::set<std::string> childNodes(const schemaPath_& path, const Recursion recursion) const override;
     std::set<std::string> moduleNodes(const module_& module, const Recursion recursion) const override;
+    std::optional<std::string> description(const std::string& path) const override;
+    std::optional<std::string> units(const std::string& path) const override;
 
     void registerModuleCallback(const std::function<std::string(const char*, const char*, const char*, const char*)>& clb);