laravel5: add README (#7221)

plugins/laravel5/README.md

+# Laravel 5 plugin
+
+This plugin adds some aliases for common [Laravel 5](https://laravel.com/docs) commands.
+
+To use it, add `laravel5` to the plugins array in your zshrc file:
+
+```zsh
+plugins=(... laravel5)
+```
+
+## Aliases
+
+| Alias     | Command                      | Description                                        |
+|-----------|------------------------------|----------------------------------------------------|
+| la5       | `php artisan`                | Main Artisan command                               |
+| la5cache  | `php artisan cache:clear`    | Flush the application cache                        |
+| la5routes | `php artisan route:list`     | List all registered routes                         |
+| la5vendor | `php artisan vendor:publish` | Publish any publishable assets from vendor package |