Fix README for v2.21.0 (#453)

* release PR for v2.21.0

* fix README

---------

Co-authored-by: ADOT Patch workflow <adot-patch-workflow@github.com>

Author: ezhang6811

README.md

@@ -33,67 +33,67 @@ Add the AWS X-Ray SDK dependencies to your pom.xml:
 <dependency>
   <groupId>com.amazonaws</groupId>
   <artifactId>aws-xray-recorder-sdk-core</artifactId>
-  <version>2.20.1</version>
+  <version>2.21.0</version>
 </dependency>
 <dependency>
   <groupId>com.amazonaws</groupId>
   <artifactId>aws-xray-recorder-sdk-apache-http</artifactId>
-  <version>2.20.1</version>
+  <version>2.21.0</version>
 </dependency>
 <dependency>
   <groupId>com.amazonaws</groupId>
   <artifactId>aws-xray-recorder-sdk-aws-sdk</artifactId>
-  <version>2.20.1</version>
+  <version>2.21.0</version>
 </dependency>
 <dependency>
   <groupId>com.amazonaws</groupId>
   <artifactId>aws-xray-recorder-sdk-aws-sdk-v2</artifactId>
-  <version>2.20.1</version>
+  <version>2.21.0</version>
 </dependency>
 <dependency>
   <groupId>com.amazonaws</groupId>
   <artifactId>aws-xray-recorder-sdk-aws-sdk-instrumentor</artifactId>
-  <version>2.20.1</version>
+  <version>2.21.0</version>
 </dependency>
 <dependency>
   <groupId>com.amazonaws</groupId>
   <artifactId>aws-xray-recorder-sdk-aws-sdk-v2-instrumentor</artifactId>
-  <version>2.20.1</version>
+  <version>2.21.0</version>
 </dependency>
 <dependency>
   <groupId>com.amazonaws</groupId>
   <artifactId>aws-xray-recorder-sdk-sql</artifactId>
-  <version>2.20.1</version>
+  <version>2.21.0</version>
 </dependency>
 <dependency>
   <groupId>com.amazonaws</groupId>
   <artifactId>aws-xray-recorder-sdk-sql-mysql</artifactId>
-  <version>2.20.1</version>
+  <version>2.21.0</version>
 </dependency>
 <dependency>
   <groupId>com.amazonaws</groupId>
   <artifactId>aws-xray-recorder-sdk-sql-postgres</artifactId>
-  <version>2.20.1</version>
+  <version>2.21.0</version>
 </dependency>
 <dependency>
   <groupId>com.amazonaws</groupId>
   <artifactId>aws-xray-recorder-sdk-spring</artifactId>
-  <version>2.20.1</version>
+  <version>2.21.0</version>
 </dependency>
 <dependency>
   <groupId>com.amazonaws</groupId>
   <artifactId>aws-xray-recorder-sdk-log4j</artifactId>
-  <version>2.20.1</version>
+  <version>2.21.0</version>
 </dependency>
 <dependency>
   <groupId>com.amazonaws</groupId>
   <artifactId>aws-xray-recorder-sdk-slf4j</artifactId>
-  <version>2.20.1</version>
+  <version>2.21.0</version>
 </dependency>
 <dependency>
   <groupId>com.amazonaws</groupId>
   <artifactId>aws-xray-recorder-sdk-metrics</artifactId>
-  <version>2.20.1</version>
+  <version>2.21.0</version>
 </dependency>
 ```