[eqdkp-plus] fix and improve guide

[noave]

Installation

• website is now at https://eqdkpplus.github.io/
• download link at https://eqdkpplus.github.io/packages/core/eqdkp-plus_2.3.39_fullpackage.zip with versioning
• point browser to /install.php
• prefer if there is a cli installation, otherwise keep it safe from attack race installation
• if web installer, make the mysql credentials and names more clear

[GodMod]

The question is, if we should keep this guide, as the development of EQdkp Plus was stopped. Therefore, there will be no security updates anymore.