chore: regenerate README (#616)

This PR was generated using Autosynth. 🌈


<details><summary>Log from Synthtool</summary>

```
2021-02-05 16:35:43,869 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-bigtable/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-02-05 16:35:44,744 synthtool [DEBUG] > Wrote metadata to .github/readme/synth.metadata/synth.metadata.

```
</details>

Full log will be available here:
https://source.cloud.google.com/results/invocations/6c71dbb7-cb82-4b8b-84bd-724ab1181866/targets

- [ ] To automatically regenerate this PR, check this box.

Author: yoshi-automation

.github/readme/synth.metadata/synth.metadata

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-bigtable.git",
-        "sha": "ea599a10e2e4fdbaf56c45b74fbb1ea5a708a7f2"
+        "sha": "3e8af747b329f6656a410160e8da14fd8227c8fc"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "16ec872dd898d7de6e1822badfac32484b5d9031"
+        "sha": "692715c0f23a7bb3bfbbaa300f7620ddfa8c47e5"
       }
     }
   ]

README.md

@@ -203,7 +203,7 @@ try {
 
 TIP: If you are experiencing version conflicts with gRPC, see [Version Conflicts](#version-conflicts).
 
-## Client request tracing: OpenCensus Tracing
+## OpenCensus Tracing
 
 Cloud Bigtable client supports [OpenCensus Tracing](https://opencensus.io/tracing/),
 which gives insight into the client internals and aids in debugging production issues.
@@ -258,8 +258,6 @@ StackdriverTraceExporter.createAndRegister(
       .setProjectId("YOUR_PROJECT_ID")
       .build());
 ```
-You can view the traces on the Google Cloud Platform Console 
-[Trace](https://console.cloud.google.com/traces) page.
 
 By default traces are [sampled](https://opencensus.io/tracing/sampling) at a rate of about 1/10,000.
 You can configure a higher rate by updating the active tracing params:
@@ -275,7 +273,7 @@ Tracing.getTraceConfig().updateActiveTraceParams(
 );
 ```
 
-## Enabling Cloud Bigtable Metrics: OpenCensus Stats
+## OpenCensus Stats
 
 Cloud Bigtable client supports [Opencensus Metrics](https://opencensus.io/stats/),
 which gives insight into the client internals and aids in debugging production issues.
@@ -378,34 +376,6 @@ BigtableDataSettings.enableOpenCensusStats();
 BigtableDataSettings.enableGfeOpenCensusStats();
 ```
 
-You can view the metrics on the Google Cloud Platform Console
-[Metrics explorer](https://console.cloud.google.com/monitoring/metrics-explorer)
-page.
-
-You can configure how frequently metrics are pushed to StackDriver and the
-[Monitored resource type](https://cloud.google.com/monitoring/api/resources) by
-updating `StackdriverStatsConfiguration`:
-
-``` java
-// Example: configuring export interval and monitored resource type
-StackdriverStatsExporter.createAndRegister(
-    StackdriverStatsConfiguration.builder()
-        .setProjectId("YOUR_PROJECT_ID")
-        // Exporting metrics every 10 seconds
-        .setExportInterval(Duration.create(10, 0))
-        // Configure monitored resource type. A common practice is to use the
-        // monitored resource objects that represent the physical resources
-        // where your application code is running. See the full list of
-        // monitored resource type here:
-        // https://cloud.google.com/monitoring/api/resources
-        .setMonitoredResource(MonitoredResource.newBuilder()
-             .setType("global")
-             .putLabels("project_id", "YOUR_PROJECT_ID")
-           .build())
-        .build()
-);
-```
-
 ## Version Conflicts
 
 google-cloud-bigtable depends on gRPC directly which may conflict with the versions brought