Add basic logical replication protocol support

README.md

@@ -25,6 +25,7 @@ Pgx supports many additional features beyond what is available through database/
 * Large object support
 * Null mapping to Null* struct or pointer to pointer.
 * Supports database/sql.Scanner and database/sql/driver.Valuer interfaces for custom types
+* Logical replication connections, including receiving WAL and sending standby status updates
 
 ## Performance
 
@@ -68,6 +69,7 @@ Then run the following SQL:
     create user pgx_md5 password 'secret';
     create user " tricky, ' } "" \ test user " password 'secret';
     create database pgx_test;
+    create user pgx_replication with replication password 'secret';
 
 Connect to database pgx_test and run:
 
@@ -100,6 +102,12 @@ If you are developing on Windows with TCP connections:
     host  pgx_test  pgx_pw    127.0.0.1/32 password
     host  pgx_test  pgx_md5   127.0.0.1/32 md5
 
+For replication testing, add the following to your postgresql.conf:
+
+    wal_level='logical'
+    max_wal_senders=5
+    max_replication_slots=5
+
 ## Version Policy
 
 pgx follows semantic versioning for the documented public API on stable releases. Branch ```v2``` is the latest stable release. ```master``` can contain new features or behavior that will change or be removed before being merged to the stable ```v2``` branch (in practice, this occurs very rarely).