PL/pg SQL: improve README => add requirements

plpgsql/README.md

@@ -1,9 +1,25 @@
+# Requirements
+You'll need:
+- PostgreSQL database, version >= 11 because PROCEDURE keyword isn't supported before [version 11](https://www.postgresql.org/docs/11/release-11.html)
+- OS user with local connection privilege to database on standard 5432 port 
+
+To use remote / local dockerized database, add ``` --host --port --username```  parameters to plsql invocation.
+
 # Setup
-Create database structure: psql -f ./structure/create.sql
+In shell:
-Load code into database psql -f ./code/update_quality.sql -d gilded_rose
+- create database: ```createdb gilded_rose```
-Load test data into database: psql -f ./test/data/load.sql -d gilded_rose
+- create item table (structure): ```psql -d gilded_rose -f ./structure/create.sql``` 
-Execute: CALL update_quality();
+- load code into database: ```psql -d gilded_rose -f ./code/update_quality.sql ```
-Check results: SELECT * FROM items;
+
+If you get this message```LINE 1: CREATE OR REPLACE PROCEDURE public.update_quality()```, your PostgreSQL version may under 11, consider upgrading.
+
+# Interactive run
+In shell:
+- load test data into database: ```psql -d gilded_rose -f ./test/data/load.sql```
+- connect to CLI: ```psql -d gilded_rose```
+- check item state: ```SELECT * FROM item;```
+- execute item update: ```CALL update_quality();```
+- check item state: ```SELECT * FROM item;```
 
 # Test
 No test code provided, only a sample of test data

plpgsql/structure/create.sql

@@ -1,7 +1,3 @@
-CREATE DATABASE gilded_rose;
-
-\connect gilded_rose;
-
 CREATE TABLE item (
  name    CHARACTER VARYING(100) NOT NULL,
  sellIn  INTEGER,