Fix doc's mysql create table statement.

[gptjddldi]

Hi, this is my first time contributing to an open-source project. I might be missing something, so please let me know if anything looks wrong — I’ll be happy to fix it right away.

In your documentation (specifically, the intro and run-db2rest-on-docker), the MySQL table creation syntax seemed different from the PostgreSQL example provided earlier. I updated the MySQL example to make it consistent.

The original MySQL example was:

CREATE TABLE `employee` (
  `emp_id` int unsigned NOT NULL AUTO_INCREMENT,
  `first_name` varchar(100) NOT NULL,
  `last_name` varchar(150) NOT NULL,
  `create_date` timestamp NULL DEFAULT CURRENT_TIMESTAMP,
  `is_active` tinyint(1) DEFAULT '1',
  PRIMARY KEY (`emp_id`)
);

When using this syntax, the following request failed.:

To resolve the issue, I modified the table definition as below:

CREATE TABLE employee (
    id INT AUTO_INCREMENT PRIMARY KEY,
    first_name VARCHAR(50) NOT NULL,
    last_name VARCHAR(50) NOT NULL,
    email VARCHAR(255) NOT NULL UNIQUE,
    created_on TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP
);