I installed to res://addons/plugin-refresher and the dropdown was empty. I noticed these errors in Output:
res://addons/plugin-refresher/plugin_refresher_plugin.gd:69 - Invalid call. Nonexistent function 'update_items' in base 'HBoxContainer'.
res://addons/plugin-refresher/plugin_refresher_plugin.gd:100 - Invalid call. Nonexistent function 'select_plugin' in base 'HBoxContainer'.
scene/resources/resource_format_text.cpp:157 - Couldn't load external resource: res://addons/godot-plugin-refresher/plugin_refresher.gd
I realized that the plugin required installing as "godot-plugin-refresher". Maybe this isn't unique to this plugin? (I'm new to godot.) Maybe would be nice to have install instructions?