Improvement: New CONTRIBUTING.md and some cleanup of the installation files

[peaklabs-dev]

Fixes: https://github.com/coollabsio/coolify/discussions/2884

Changes:

• Feat: Brand new, much better, more detailed and beginner friendly contribution guide.
• Fix: Renamed CONTRIBUTION.md to CONTRIBUTING.md to conform to the Community Standards and the Contributing Guidelines here Community Standards.
• Fix: Added DB_HOST=host.docker.internal to .env.development.example to fix a DB migration error on MacOS: Error Code:

php artisan migrate

   Illuminate\Database\QueryException

  SQLSTATE[08006] [7] could not translate host name "postgres" to address: nodename nor servname provided, or not known (Connection: pgsql, SQL: select c.relname as name, n.nspname as schema, pg_total_relation_size(c.oid) as size, obj_description(c.oid, 'pg_class') as comment from pg_class c, pg_namespace n where c.relkind in ('r', 'p') and n.oid = c.relnamespace and n.nspname not in ('pg_catalog', 'information_schema') order by c.relname)

  at vendor/laravel/framework/src/Illuminate/Database/Connection.php:813
    809▕                     $this->getName(), $query, $this->prepareBindings($bindings), $e
    810▕                 );
    811▕             }
    812▕
  ➜ 813▕             throw new QueryException(
    814▕                 $this->getName(), $query, $this->prepareBindings($bindings), $e
    815▕             );
    816▕         }
    817▕     }

      +40 vendor frames

  41  artisan:35
      Illuminate\Foundation\Console\Kernel::handle(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))

• Fix: Added soketi health check to Coolify install compose files
• Improvement: Make sure to generate Postgres username securely instead of using coolify as a username by default in production compose
• Improvement: Made formatting changes in the compose files (grouped all PHP variables, all APP variables...)