minor #746 Clarify the dump-env exception message (apfelbox)

This PR was merged into the 1.12-dev branch.

Discussion
----------

Clarify the dump-env exception message

`--env` would be an option, but `env` is an argument.

And the suggested/hinted

```bash
composer dump-env --env=prod
```

doesn't work

Commits
-------

dd2aea1 Clarify the dump-env exception message

Author: nicolas-grekas

src/Command/DumpEnvCommand.php

@@ -108,7 +108,7 @@ private function loadEnv(string $path, ?string $env): array
             }
 
             if (!$env) {
-                throw new \RuntimeException('Please provide the name of the environment either by using the "--env" command line argument or by defining the "APP_ENV" variable in the ".env.local" file.');
+                throw new \RuntimeException('Please provide the name of the environment either by passing it as command line argument or by defining the "APP_ENV" variable in the ".env.local" file.');
             }
 
             if (method_exists($dotenv, 'loadEnv')) {

tests/Command/DumpEnvCommandTest.php

@@ -131,7 +131,7 @@ public function testRequiresToSpecifyEnvArgumentWhenLocalFileDoesNotSpecifyAppEn
 
         $command = $this->createCommandDumpEnv();
         $this->expectException(\RuntimeException::class);
-        $this->expectExceptionMessage('Please provide the name of the environment either by using the "--env" command line argument or by defining the "APP_ENV" variable in the ".env.local" file.');
+        $this->expectExceptionMessage('Please provide the name of the environment either by passing it as command line argument or by defining the "APP_ENV" variable in the ".env.local" file.');
 
         try {
             $command->execute([]);