added any type visitor and converter

README.md

@@ -1,3 +1,45 @@
 # query
 
-A fluent sql query builder
+A fluent sql query builder
+
+Object definition
+```cpp
+struct airplane
+{
+  unsigned long id;
+  std::string brand;
+  std::string model;
+
+  template<class Operator>
+  void process(Operator &op) {
+    namespace field = matador::utils::access;
+    field::primary_key(op, "id", id);
+    field::attribute(op, "brand", brand, 255);
+    field::attribute(op, "model", model, 255);
+  }
+};
+```
+```cpp
+connection_pool<connection> pool("sqlite://sqlite.db", 4);
+session s(pool);
+
+// register entity
+s.attach<airplane>("airplane")
+
+// create all tables
+s.create();
+
+// insert
+s.insert<airplane>(1, "Airbus", "A380");
+s.insert<airplane>(2, "Boeing", "748");
+s.insert<airplane>(3, "Boeing", "707");
+
+s.update<airplane>().set({"model", "747"}).where("id"_col == 2);
+
+auto result = s.select<airplane>().where("brand"_col == "Boeing");
+
+for (const auto &plane : result) {
+  std::cout << "airplane: " << plane->brand << " - " << plane->model << "\n";
+}
+
+```