Improve the documentation about deploying a Symfony app

[mykiwi]

Hi,

I just notice something in the doc that maybe we could improve.

The Symfony guide says nothing specific for the deployment part, and so suggest doingcomposer install --prefer-dist --optimize-autoloader --no-dev

But we should probably suggest doing APP_ENV=prod composer install --prefer-dist --optimize-autoloader --no-dev (or add --no-scripts option) to avoid this kind of errors:

$ composer install --prefer-dist --optimize-autoloader --no-dev
...

Executing script cache:clear [KO]
 [KO]
Script cache:clear returned with error code 255
!!  Symfony\Component\ErrorHandler\Error\ClassNotFoundError {#63
!!    #message: """
!!      Attempted to load class "....Bundle" from namespace "...\...Bundle".\n
!!      Did you forget a "use" statement for another namespace?
!!      """
!!    #code: 0
!!    #file: "./vendor/symfony/framework-bundle/Kernel/MicroKernelTrait.php"
!!    #line: 74
!!    trace: {
!!      ./vendor/symfony/framework-bundle/Kernel/MicroKernelTrait.php:74 { …}
!!      ./vendor/symfony/http-kernel/Kernel.php:371 { …}
!!      ./vendor/symfony/http-kernel/Kernel.php:128 { …}
!!      ./vendor/symfony/framework-bundle/Console/Application.php:168 { …}
!!      ./vendor/symfony/framework-bundle/Console/Application.php:74 { …}
!!      ./vendor/symfony/console/Application.php:142 { …}
!!      ./bin/console:43 {
!!        › $application = new Application($kernel);
!!        › $application->run($input);
!!        › 
!!        arguments: {
!!          $input: Symfony\Component\Console\Input\ArgvInput {#3 …}
!!        }
!!      }
!!    }
!!  }
!!  2020-11-19T10:35:11+00:00 [critical] Uncaught Error: Class '...\...Bundle' not found
!!
Script @auto-scripts was called via post-install-cmd

Reproductible example:

git clone [email protected]:symfony/demo.git sfdemo
cd sfdemo
composer install --prefer-dist --optimize-autoloader --no-dev # result: Script cache:clear returned with error code 255 - Attempted to load class "DebugBundle" from namespace "Symfony\Bundle\DebugBundle"

WDYT? Should I create a PR and add something about it before redirecting the user to the deployment page?

[mnapoli]

:+1: that makes sense

[mnapoli]

The docs have changed since then, I'll close this issue for cleanup.