docs: improve Azure.Provisioning.Monitor README with resource types and next steps

## Summary

Improves the `Azure.Provisioning.Monitor` README (introduced in #57725) to fill two documentation gaps:

### Changes

**Key concepts — supported resource types table**

The `## Key concepts` section previously had only a single boilerplate sentence. Users discovering the library had no way to know what Azure Monitor resources were available without reading the generated API. A table of all 16 `ProvisionableResource` types with brief descriptions has been added:

| Resource | Description |
|---|---|
| `ActionGroup` | Defines a set of notification actions triggered by alerts |
| `ActivityLogAlert` | Creates alerts based on Azure activity log events |
| `AlertRule` | Classic metric alert rule for Azure Monitor metrics |
| `AutoscaleSetting` | Configures automatic scaling of compute resources |
| `DataCollectionEndpoint` | Defines an endpoint for data collection pipelines |
| `DataCollectionRule` | Specifies how data is collected and routed to destinations |
| `DataCollectionRuleAssociation` | Associates a data collection rule with a monitored resource |
| `DiagnosticSetting` | Routes diagnostic logs and metrics to storage, event hubs, or Log Analytics |
| `LogProfile` | Classic log profile for routing activity logs (legacy) |
| `MetricAlert` | Creates alerts based on Azure Monitor metric thresholds or dynamic conditions |
| `MonitorPrivateEndpointConnection` | Manages private endpoint connections for Azure Monitor Private Link |
| `MonitorPrivateLinkScope` | Defines the scope of a Private Link configuration for Azure Monitor |
| `MonitorPrivateLinkScoped` | Associates resources with a Monitor Private Link scope |
| `MonitorWorkspace` | Azure Monitor workspace for storing Prometheus metrics |
| `PipelineGroup` | Groups data collection pipelines for centralized management |
| `ScheduledQueryRule` | Creates alerts based on Log Analytics or metrics queries |

**Next steps — useful links**

The `## Next steps` section was entirely empty. Three links were added:
- Azure Monitor overview documentation
- Azure Developer CLI getting-started guide (for `azd` deployments)
- Azure Monitor quickstart templates on GitHub

### No behavior changes

Documentation-only change; no code was modified.

### Reviewers

cc `@ArcturusZhang` `@ArthurMa1978` `@m-nash` (Azure.Provisioning CODEOWNERS)

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---

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> The changes have been pushed to branch `docs/azure-provisioning-monitor-readme-improvements-386d100ba96aaa09`.
>
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Show patch preview (73 of 73 lines)

```diff
From 642d787ce53ecc47895c292a5095f9fa2c2fd760 Mon Sep 17 00:00:00 2001
From: "github-actions[bot]"
Date: Fri, 3 Apr 2026 08:40:14 +0000
Subject: [PATCH] docs: improve Azure.Provisioning.Monitor README with resource
types and next steps

- Add table of all 16 supported resource types with descriptions in Key concepts
- Fill in the empty Next steps section with links to Azure Monitor docs,
Azure Developer CLI, and quickstart templates

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
.../Azure.Provisioning.Monitor/README.md | 30 ++++++++++++++++++-
1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/sdk/monitor/Azure.Provisioning.Monitor/README.md b/sdk/monitor/Azure.Provisioning.Monitor/README.md
index 6dc8ddd70..bbe729e83 100644
--- a/sdk/monitor/Azure.Provisioning.Monitor/README.md
+++ b/sdk/monitor/Azure.Provisioning.Monitor/README.md
@@ -22,6 +22,27 @@ dotnet add package Azure.Provisioning.Monitor --prerelease

This library allows you to specify your infrastructure in a declarative style using dotnet. You can then use azd to deploy your infrastructure to Azure directly without needing to write or maintain bicep or arm templates.

+The following Azure Monitor resource types are supported:
+
+| Resource | Description |
+|---|---|
+| `ActionGroup` | Defines a set of notification actions triggered by alerts |
+| `ActivityLogAlert` | Creates alerts based on Azure activity log events (e.g., service health, resource changes) |
+| `AlertRule` | Classic metric alert rule for Azure Monitor metrics |
+| `AutoscaleSetting` | Configures automatic scaling of compute resources based on metrics |
+| `DataCollectionEndpoint` | Defines an endpoint for data collection pipelines |
+| `DataCollectionRule` | Specifies how data is collected and routed to destinations |
+| `DataCollectionRuleAssociation` | Associates a data collection rule with a monitored resource |
+| `DiagnosticSetting` | R
... (truncated)
```