fixed #1068 drush need mysql-client installed

* hackel-change-mysql-version:
  Add documentation on the MYSQL_VERSION variable.
  Allow specifying the version of MySQL to install in .env file.

Merge branch 'change-mysql-version' of https://github.com/hackel/laradock into hackel-change-mysql-version

* 'change-mysql-version' of https://github.com/hackel/laradock:
  Add documentation on the MYSQL_VERSION variable.
  Allow specifying the version of MySQL to install in .env file.

Xdebug configuration for Linux on PhpStorm

Added images and explanations for setting up remote debugging for PhpStorm on Linux

Also modified slightly Install Xdebug section to keep reading consistent

Integrating docker sync

added support for docker-sync and added sync.sh script to simplify the use of docker-sync with laradock