Add limits of libpq (#142)

Author: hfhbd

README.md

@@ -6,6 +6,8 @@ You can use the driver with [SQLDelight](https://github.com/cashapp/sqldelight),
 
 - [Source code](https://github.com/hfhbd/postgres-native-sqldelight)
 
+> Keep in mind, until now, this is only a single-threaded wrapper over libpq using 1 connection only. There is no connection pool nor multithread support (like JDBC or R2DBC).
+
 ## Install
 
 You need `libpq` installed and available in your `$PATH`.