Update project page Drush install commands, remove easychart.org

Problem/Motivation

Fantastic module, it makes it really easy to create beautiful charts!

On the project page https://www.drupal.org/project/easychart → , under "Installation", it's not clear what some of the Drush commands mean ( like eci?), so maybe it's better to use the real and not abbreviation version of commands?

Also, the web site http://www.easychart.org/ is gone, and should be removed.

Steps to reproduce

Proposed resolution

1. Update Installation commands:
   

   Installation

   Use Drush to install the module, and its required dependencies:

   drush install easychart -y
   drush easychart:install
   

   Clear CSS and JavaScript cache after installing the JavaScript dependencies:

   drush cache:rebuild

   For non-Drush installation, refer to the README file.

2. Remove https://www.easychart.org/

Remaining tasks

User interface changes

API changes

Data model changes