godot-demo-projects/plugins
..
custom_dock
custom_import_plugin
custom_material_creator
custom_node
readme.txt

readme.txt

To install these, copy each of these folders to a folder:

addons/

inside your projects, example:

addons/custom_node

To distribute and install from UI, make a zip that contains the folder,
example:

zip -r custom_node.zip custom_node/*