Update LNM guidance intro (#132)

## Purpose
Clarify details of LNM guidance

## Does this introduce a breaking change?
<!-- Mark one with an "x". -->
```
[ ] Yes
[x] No
```

## Pull Request Type
What kind of change does this Pull Request introduce?

<!-- Please check the one that applies to this PR using "x". -->
```
[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[x] Documentation content changes
[ ] Other... Please describe:
```

Author: dominicbetts

samples/layered-networking/README.md

@@ -2,9 +2,11 @@
 
 In industries like manufacturing, you often see segmented networking architectures that create layers. These layers minimize or block lower-level segments from connecting to the internet (for example, [Purdue Network Architecture](https://en.wikipedia.org/wiki/Purdue_Enterprise_Reference_Architecture)).
 
-This article demonstrates that Azure IoT Operations can be installed and managed in a layered network using open, industry-recognized software. It does not recommend specific practices or provide production-ready implementation, configuration, or operations details. For those details, see the [Azure IoT Operations production checklist](https://learn.microsoft.com/en-us/azure/iot-edge/production-checklist). This article also does not make recommendations about networking architecture.
+This guidance describes the test environment Microsoft uses to validate Azure IoT Operations deployments in a layered network using open, industry-recognized software. The guidance doesn't recommend specific practices or provide production-ready implementation, configuration, or operations details. The guidance doesn't make recommendations about production networking architecture.
 
-This article covers:
+To learn more about how to prepare for a production-ready deployment of Azure IoT Operations, see the [Azure IoT Operations production checklist](https://learn.microsoft.com/en-us/azure/iot-edge/production-checklist).
+
+This guidance covers:
 
 - Kubernetes-based configuration and compatibility with networking primitives
 - Connecting devices in layered networks at scale to [Azure Arc](https://learn.microsoft.com/en-us/azure/azure-arc/) for remote management and configuration from a single Azure control plane
@@ -14,7 +16,7 @@ This article covers:
 
 ## Key features
 
-This article demonstrates how to deploy Azure IoT Operations in a layered network environment and uses it to route telemetry from assets on the edge to Azure services in the cloud.
+This guidance demonstrates how to deploy Azure IoT Operations in a layered network environment in a test environment and use it to route telemetry from assets on the edge to Azure services in the cloud.
 
 ## Next steps