minor #16908 [Dotenv] [SymfonyRuntime] option 'dotenv_overload' mention (nedvajz)

This PR was merged into the 5.4 branch.

Discussion
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[Dotenv] [SymfonyRuntime] option 'dotenv_overload' mention

Found out, that option `dotenv_overload` is not mentioned in documentation since [5.4](https://github.com/symfony/runtime/blob/5.4/CHANGELOG.md) when it was added.

So here is update for documentation.

Commits
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577a261 [SymfonyRuntime] option 'dotenv_overload' mention

Author: javiereguiluz

components/runtime.rst

@@ -337,6 +337,8 @@ The following options are supported by the ``SymfonyRuntime``:
     To disable looking for ``.env`` files.
 ``dotenv_path`` (default: ``.env``)
     To define the path of dot-env files.
+``dotenv_overload`` (default: ``false``)
+    To tell Dotenv whether to override ``.env`` vars with ``.env.local`` (or other ``.env.*``)
 ``use_putenv``
     To tell Dotenv to set env vars using ``putenv()`` (NOT RECOMMENDED).
 ``prod_envs`` (default: ``["prod"]``)