docs: how to handle deprecation of max_concurrency

Author: ahamez

docs/resources/container.md

@@ -76,7 +76,7 @@ The following arguments are supported:
 
 - `registry_sha256` - (Optional) The sha256 of your source registry image, changing it will re-apply the deployment. Can be any string.
 
-- `max_concurrency` - (Optional) The maximum number of simultaneous requests your container can handle at the same time.
+- `max_concurrency` - (Deprecated) The maximum number of simultaneous requests your container can handle at the same time. Use `scaling_option.concurrent_requests_threshold` instead.
 
 - `protocol` - (Optional) The communication [protocol](https://www.scaleway.com/en/developers/api/serverless-containers/#path-containers-update-an-existing-container) `http1` or `h2c`. Defaults to `http1`.