Use reexported postgres for NoTls in examples

Author: dpetersen

README.md

@@ -11,8 +11,7 @@ r2d2-postgres
 
 ```rust
 use std::thread;
-use postgres::{NoTls, Client};
-use r2d2_postgres::PostgresConnectionManager;
+use r2d2_postgres::{postgres::NoTls, PostgresConnectionManager};
 
 fn main() {
     let manager = PostgresConnectionManager::new(

src/lib.rs

@@ -14,8 +14,7 @@ use r2d2::ManageConnection;
 ///
 /// ```no_run
 /// use std::thread;
-/// use postgres::{NoTls, Client};
-/// use r2d2_postgres::PostgresConnectionManager;
+/// use r2d2_postgres::{postgres::NoTls, PostgresConnectionManager};
 ///
 /// fn main() {
 ///     let manager = PostgresConnectionManager::new(