Update README.md

Author: lganzzzo

README.md

@@ -1,4 +1,59 @@
 # oatpp-postgresql [![Build Status](https://dev.azure.com/lganzzzo/lganzzzo/_apis/build/status/oatpp.oatpp-postgresql?branchName=master)](https://dev.azure.com/lganzzzo/lganzzzo/_build/latest?definitionId=31&branchName=master)
 
-Oat++ ORM adapter for PostgreSQL
+Oat++ ORM adapter for PostgreSQL.  
+*Note: this alpha version, which means that not all PostgreSQL data-types are supported.*
 
+More about Oat++:
+
+- [Oat++ Website](https://oatpp.io/)
+- [Oat++ Github Repository](https://github.com/oatpp/oatpp)
+- [Oat++ ORM](https://oatpp.io/docs/components/orm/)
+
+## Build And Install
+
+*Note: you need to install the main [oatpp](https://github.com/oatpp/oatpp) module and PostgreSQL dev package first.*
+
+- Clone this repository.
+- In the root of the repository run:
+   ```bash
+   mkdir build && cd build
+   cmake ..
+   make install
+   ```
+   
+## API
+
+Detailed documentation on Oat++ ORM you can find [here](https://oatpp.io/docs/components/orm/).
+
+### Connect to Database
+
+All you need to start using oatpp ORM with PostgreSQL is to create `oatpp::postgresql::Executor` and provide it to your `DbClient`.
+
+```cpp
+#include "db/MyClient.hpp"
+#include "oatpp-postgresql/orm.hpp"
+
+class AppComponent {
+public:
+  
+  /**
+   * Create DbClient component.
+   */
+  OATPP_CREATE_COMPONENT(std::shared_ptr<db::MyClient>, myDatabaseClient)([] {
+    /* Create database-specific ConnectionProvider */
+    auto connectionProvider = std::make_shared<oatpp::postgresql::ConnectionProvider>("<connection-string>");    
+  
+    /* Create database-specific ConnectionPool */
+    auto connectionPool = oatpp::postgresql::ConnectionPool::createShared(connectionProvider, 
+                                                                          10 /* max-connections */, 
+                                                                          std::chrono::seconds(5) /* connection TTL */);
+    
+    /* Create database-specific Executor */
+    auto executor = std::make_shared<oatpp::postgresql::Executor>(connectionPool);
+  
+    /* Create MyClient database client */
+    return std::make_shared<MyClient>(executor);
+  }());
+
+};
+```