Set up package skeleton

[krzysztofrewak]

I would like to see all required steps from documentation (https://laravel.com/docs/11.x/packages) done in scope of this task. This includes:

• [x] autodiscoverable service provider
• [ ] default configuration file
• [x] readme introduction

Package will be published as blumilksoftware/laravel-heatmap in Packagist.

[krzysztofrewak]

Not all ACs were finished. I'm reopening this task.