After creating a module and you are sure your module module will be used by other developers. You can push your module to github or bitbucket and after that you can submit your module to the packagist website.
You can follow this step to publish your module.
There is also a way for you to have your modules be installed in the
Modules/ automatically using joshbrw/laravel-module-installer. Simply require this package on your module, and set the
type key in the
composer.json file to