minor symfony#52286 [Dotenv] Add PHPDoc for $overrideExistingVars (alexandre-daubois)

This PR was merged into the 5.4 branch.

Discussion
----------

[Dotenv] Add PHPDoc for `$overrideExistingVars`

| Q             | A
| ------------- | ---
| Branch?       | 5.4
| Bug fix?      | no
| New feature?  | no
| Deprecations? | no
| Issues        | -
| License       | MIT

Following symfony/symfony-docs#19082 (comment)

Commits
-------

218a4ac [Dotent] Add PHPDoc for `$overrideExistingVars`

Author: nicolas-grekas

src/Symfony/Component/Dotenv/Dotenv.php

@@ -98,10 +98,11 @@ public function load(string $path, string ...$extraPaths): void
      * .env.local is always ignored in test env because tests should produce the same results for everyone.
      * .env.dist is loaded when it exists and .env is not found.
      *
-     * @param string      $path       A file to load
-     * @param string|null $envKey     The name of the env vars that defines the app env
-     * @param string      $defaultEnv The app env to use when none is defined
-     * @param array       $testEnvs   A list of app envs for which .env.local should be ignored
+     * @param string      $path                 A file to load
+     * @param string|null $envKey               The name of the env vars that defines the app env
+     * @param string      $defaultEnv           The app env to use when none is defined
+     * @param array       $testEnvs             A list of app envs for which .env.local should be ignored
+     * @param bool        $overrideExistingVars Whether existing environment variables set by the system should be overridden
      *
      * @throws FormatException when a file has a syntax error
      * @throws PathException   when a file does not exist or is not readable
@@ -182,7 +183,7 @@ public function overload(string $path, string ...$extraPaths): void
      * Sets values as environment variables (via putenv, $_ENV, and $_SERVER).
      *
      * @param array $values               An array of env variables
-     * @param bool  $overrideExistingVars true when existing environment variables must be overridden
+     * @param bool  $overrideExistingVars Whether existing environment variables set by the system should be overridden
      */
     public function populate(array $values, bool $overrideExistingVars = false): void
     {