[AWS] Doc update for CF updates (#696)

* [AWS] Doc update for CF updates

* [AWS] Move doc updates to Troubleshooting section

aws/logs_monitoring/README.md

@@ -133,8 +133,10 @@ If you can't install the Forwarder using the provided CloudFormation template, y
 ### Upgrade to a new version
 
 1. Find the [datadog-forwarder (if you didn't rename it)][5] CloudFormation stack. If you installed the Forwarder as part of the [Datadog AWS integration stack][6], make sure to update the nested Forwarder stack instead of the root stack.
-2. Find the actual Forwarder Lambda function from the CloudFormation stack's "Resources" tab, navigate to its configuration page. Note down the value of the tag `dd_forwarder_version`, such as `3.3.0`, in case you run into issues with the new version and need to rollback.
-3. Update the stack using template `https://datadog-cloudformation-template.s3.amazonaws.com/aws/forwarder/latest.yaml`. You can also replace `latest` with a specific version, such as `3.0.2.yaml`, if needed. Make sure to review the changesets before applying the update.
+2. Find the actual Forwarder Lambda function from the CloudFormation stack's "Resources" tab, navigate to its configuration page. Note down the value of the tag `dd_forwarder_version`, such as `3.73.0`, in case you run into issues with the new version and need to rollback.
+3. Update the stack using template `https://datadog-cloudformation-template.s3.amazonaws.com/aws/forwarder/latest.yaml`. You can also replace `latest` with a specific version, such as `3.73.0.yaml`, if needed. Make sure to review the changesets before applying the update.
+
+If you encounter issues upgrading to the latest version, check the Troubleshooting section.
 
 ### Upgrade an older version to +3.74.0
 
@@ -179,10 +181,17 @@ Datadog recommends adjusting your Forwarder settings through CloudFormation rath
 
 Don't forget to check if the issue has already been fixed in the recent [releases][9].
 
+### Logging
+
 Set the environment variable `DD_LOG_LEVEL` to `debug` on the Forwarder Lambda function to enable detailed logging temporarily (don't forget to remove it). The debugging logs should be able to show you the exact event payload the Lambda function receives and the data (log, metric or trace) payload that is sent to Datadog.
 
 You can also add additional logging or code for deeper investigation. Find instructions for building Forwarder code with local changes from the [contributing](#contributing) section.
 
+### Issue updating the forwarder
+
+Manually updating the `.zip` code of the Forwarder may cause conflicts with Cloudformation updates for Forwarder installations where the code is packaged in a Lambda layer (default installation choice from version `3.33.0`) and cause invocation errors. In this case, updating the stack through Cloudformation to the latest available twice in a row (first with `InstallAsLayer` set to `false`, and then to `true`) should solve the issue as it will remove any `.zip` remnants and install the latest layer available.
+
+
 If you still couldn't figure out, please create a ticket for [Datadog Support][10] with a copy of debugging logs.
 
 ## Contributing