I saw this message today when accessing my plugin page:
So, how do I create this if I want to update my own plugins that’s hosted on wordpress?
This message is created by W3_Total_Cache->in_plugin_update_message() hooked to "in_plugin_update_message-$file"in wp_plugin_update_row().
It does some nifties to parse readme and display info from changelog, but overall you can just echo some stuff as with any other hook.