Update Readme with Batch Query Example (Azure#26900)

### Packages impacted by this PR

@azure/monitor-query

### Issues associated with this PR

N/A

### Describe the problem that is addressed by this PR

This PR is to update the Readme file with the example of batch metrics
query.

### What are the possible designs available to address the problem? If
there are more than one possible design, why was the one in this PR
chosen?

No special design considerations for this issue. This is just to update
the Readme

### Are there test cases added in this PR? _(If not, why?)_

N/A

### Provide a list of related PRs _(if any)_

N/A

### Command used to generate this PR:**_(Applicable only to SDK release
request PRs)_

### Checklists
- [X] Added impacted package name to the issue description
- [ ] Does this PR needs any fixes in the SDK Generator?** _(If so,
create an Issue in the
[Autorest/typescript](https://github.com/Azure/autorest.typescript)
repository and link it here)_
- [ ] Added a changelog (if necessary)

---------

Co-authored-by: Scott Addie <10702007+scottaddie@users.noreply.github.com>

Author: sarangan12

sdk/monitor/monitor-query/README.md

@@ -46,13 +46,20 @@ An authenticated client is required to query Logs or Metrics. To authenticate, t
 
 ```ts
 import { DefaultAzureCredential } from "@azure/identity";
-import { LogsQueryClient, MetricsQueryClient } from "@azure/monitor-query";
+import { LogsQueryClient, MetricsQueryClient, MetricsBatchQueryClient } from "@azure/monitor-query";
 
 const credential = new DefaultAzureCredential();
 
-const logsQueryClient = new LogsQueryClient(credential);
+const logsQueryClient: LogsQueryClient = new LogsQueryClient(credential);
+// or
+const metricsQueryClient: MetricsQueryClient = new MetricsQueryClient(credential);
 // or
-const metricsQueryClient = new MetricsQueryClient(credential);
+const batchEndPoint: string = "<YOUR_METRICS_ENDPOINT>"; //for example, https://eastus.metrics.monitor.azure.com/
+
+const metricsBatchQueryClient: MetricsBatchQueryClient = new MetricsBatchQueryClient(
+  batchEndPoint,
+  credential
+);
 ```
 
 #### Configure clients for non-public Azure clouds
@@ -110,6 +117,7 @@ Each set of metric values is a time series with the following characteristics:
 - [Metrics query](#metrics-query)
   - [Handle metrics query response](#handle-metrics-query-response)
   - [Example of handling response](#example-of-handling-response)
+- [Batch metrics query](#batch-metrics-query)
 
 ### Logs query
 
@@ -716,6 +724,32 @@ main().catch((err) => {
 
 A full sample can be found [here](https://github.com/Azure/azure-sdk-for-js/blob/main/sdk/monitor/monitor-query/samples/v1/typescript/src/metricsQuery.ts).
 
+### Batch metrics query
+
+The following example executes multiple metrics queries in a single request using the `MetricsBatchQueryClient.queryBatch` method:
+
+```ts
+let resourceIds: string[] = [
+  "/subscriptions/0000000-0000-000-0000-000000/resourceGroups/test/providers/Microsoft.OperationalInsights/workspaces/test-logs",
+  "/subscriptions/0000000-0000-000-0000-000000/resourceGroups/test/providers/Microsoft.OperationalInsights/workspaces/test-logs2",
+];
+let metricsNamespace: string = "<YOUR_METRICS_NAMESPACE>";
+let metricNames: string[] = ["requests", "count"];
+const batchEndPoint: string = "<YOUR_METRICS_ENDPOINT>"; //for example, https://eastus.metrics.monitor.azure.com/
+
+const credential = new DefaultAzureCredential();
+const metricsBatchQueryClient: MetricsBatchQueryClient = new MetricsBatchQueryClient(
+  batchEndPoint,
+  credential
+);
+
+const result: MetricResultsResponseValuesItem[] = await metricsBatchQueryClient.queryBatch(
+  resourceIds,
+  metricsNamespace,
+  metricNames
+);
+```
+
 ## Troubleshooting
 
 To diagnose various failure scenarios, see the [troubleshooting guide](https://github.com/Azure/azure-sdk-for-js/blob/main/sdk/monitor/monitor-query/TROUBLESHOOTING.md).