With Matomo 4 Custom Variables plugin will no longer be part of the core. To still have it available, we need to publish the plugin to the Marketplace.

Before doing this, we need at least

• Apply required changes to have the plugin independent from core (--> see Prepare plugin for Marketplace #1)
• Create a README file with a proper description of the plugin
• Add some screenshots for the plugin
• Setup the marketplace hook in this repo
• Release a new version