Add a tip about hooks to docs

Signed-off-by: peterdeme <[email protected]>

docs/concepts/stack/stack-settings.md

@@ -49,6 +49,10 @@ Note here that all hooks, including the `after_run` ones, execute on the worker.
 
 These commands may serve one of two general purposes - either to make some modifications to your workspace (eg. set up symlinks, move files around etc.) or perhaps to run validations using something like [`tfsec`](https://github.com/tfsec/tfsec){: rel="nofollow"}, [`tflint`](https://github.com/terraform-linters/tflint){: rel="nofollow"} or `terraform fmt`.
 
+!!! tip
+    We don’t recommend using newlines (`\n`) in hooks. The reason is that we are chaining the Spacelift commands (eg. `terraform plan`) commands with pre/post hooks with double ampersand (`&&`) and using commands separated by newlines can cause a non-zero exit code by a command to be hidden if the last command in the newline-separated block succeeds.
+    If you'd like to run multiple commands in a hook, add multiple hooks instead.
+
 !!! danger
     When a run resumes after having been paused for any reason (e.g., confirmation, approval policy), the remaining phases are run in a new container. As a result, any tool installed in a phase that occurred before the pause won't be available in the subsequent phases. A better way to achieve this would be to bake the tool into a [custom runner image](../../integrations/docker.md#customizing-the-runner-image).