added 'table example' for DBServer_PGSQL

extensions/DBServer-PostgreSQL/db_create_example.sql

+CREATE TABLE main_history (
+  id PRIMARY KEY NOT NULL,
+  date date NOT NULL,
+  time time NOT NULL,
+  time_usec int NOT NULL CHECK (time_usec >= 0),
+  sensor_id int NOT NULL,
+  value double precision NOT NULL,
+  node int NOT NULL,
+  confirm int DEFAULT NULL,
+  PRIMARY KEY (id)
+);