chore: update readme file (#2199)

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Fixes #<issue_number_goes_here> ☕️

If you write sample code, please follow the [samples format](
https://togithub.com/GoogleCloudPlatform/java-docs-samples/blob/main/SAMPLE_FORMAT.md).

Author: mutianf

.readme-partials.yml

@@ -115,7 +115,7 @@ custom_content: |
 
   TIP: If you are experiencing version conflicts with gRPC, see [Version Conflicts](#version-conflicts).
 
-  ## Enabling client side metrics
+  ## Client side metrics
 
   Cloud Bigtable client supports publishing client side metrics to
   [Cloud Monitoring](https://cloud.google.com/monitoring/docs/monitoring-overview) under the
@@ -124,8 +124,6 @@ custom_content: |
   This feature is available once you upgrade to version 2.16.0 and above.
   Follow the guide on https://cloud.google.com/bigtable/docs/client-side-metrics-setup to enable.
 
-  ## Client side metrics
-
   Since version 2.38.0, [client side metrics](https://cloud.google.com/bigtable/docs/client-side-metrics)
   is enabled by default. This feature collects useful telemetry data in the client and is recommended to
   use in conjunction with server-side metrics to get a complete, actionable view of your Bigtable
@@ -136,7 +134,7 @@ custom_content: |
 
   You can opt-out client side metrics with the following settings:
 
-  ```
+  ```java
   BigtableDataSettings settings = BigtableDataSettings.newBuilder()
           .setProjectId("my-project")
           .setInstanceId("my-instance")
@@ -229,7 +227,7 @@ custom_content: |
   If your application already has OpenCensus Tracing integration and you want to disable Bigtable
   traces, you can do the following:
 
-  ```
+  ```java
   public static class MySampler extends Sampler {
 
       private final Sampler childSampler;
@@ -259,7 +257,7 @@ custom_content: |
   ```
 
   And use this sampler in your trace config:
-  ```
+  ```java
   Tracing.getTraceConfig().updateActiveTraceParams(
           Tracing.getTraceConfig().getActiveTraceParams().toBuilder()
                   .setSampler(new MySampler(Samplers.probabilitySampler(0.1)))

README.md

@@ -215,7 +215,7 @@ try {
 
 TIP: If you are experiencing version conflicts with gRPC, see [Version Conflicts](#version-conflicts).
 
-## Enabling client side metrics
+## Client side metrics
 
 Cloud Bigtable client supports publishing client side metrics to
 [Cloud Monitoring](https://cloud.google.com/monitoring/docs/monitoring-overview) under the
@@ -224,8 +224,6 @@ Cloud Bigtable client supports publishing client side metrics to
 This feature is available once you upgrade to version 2.16.0 and above.
 Follow the guide on https://cloud.google.com/bigtable/docs/client-side-metrics-setup to enable.
 
-## Client side metrics
-
 Since version 2.38.0, [client side metrics](https://cloud.google.com/bigtable/docs/client-side-metrics)
 is enabled by default. This feature collects useful telemetry data in the client and is recommended to
 use in conjunction with server-side metrics to get a complete, actionable view of your Bigtable
@@ -236,7 +234,7 @@ in Cloud Monitoring.
 
 You can opt-out client side metrics with the following settings:
 
-```
+```java
 BigtableDataSettings settings = BigtableDataSettings.newBuilder()
         .setProjectId("my-project")
         .setInstanceId("my-instance")
@@ -329,7 +327,7 @@ Tracing.getTraceConfig().updateActiveTraceParams(
 If your application already has OpenCensus Tracing integration and you want to disable Bigtable
 traces, you can do the following:
 
-```
+```java
 public static class MySampler extends Sampler {
 
     private final Sampler childSampler;
@@ -359,7 +357,7 @@ public static class MySampler extends Sampler {
 ```
 
 And use this sampler in your trace config:
-```
+```java
 Tracing.getTraceConfig().updateActiveTraceParams(
         Tracing.getTraceConfig().getActiveTraceParams().toBuilder()
                 .setSampler(new MySampler(Samplers.probabilitySampler(0.1)))