Update README to use 2.20.1 release

Author: emlaver

README.md

@@ -36,14 +36,14 @@ This is the official Cloudant library for Java.
 Gradle:
 ```groovy
 dependencies {
-    compile group: 'com.cloudant', name: 'cloudant-client', version: '2.19.2'
+    compile group: 'com.cloudant', name: 'cloudant-client', version: '2.20.1'
 }
 ```
 
 Gradle with [optional `okhttp-urlconnection` dependency](#optional-okhttp-dependency):
 ```groovy
 dependencies {
-    compile group: 'com.cloudant', name: 'cloudant-client', version: '2.19.2'
+    compile group: 'com.cloudant', name: 'cloudant-client', version: '2.20.1'
     compile group: 'com.squareup.okhttp3', name: 'okhttp-urlconnection', version: '3.12.12'
 }
 ```
@@ -53,7 +53,7 @@ Maven:
 <dependency>
   <groupId>com.cloudant</groupId>
   <artifactId>cloudant-client</artifactId>
-  <version>2.19.2</version>
+  <version>2.20.1</version>
 </dependency>
 ~~~
 
@@ -63,7 +63,7 @@ Maven with [optional `okhttp-urlconnection` dependency](#optional-okhttp-depende
 <dependency>
   <groupId>com.cloudant</groupId>
   <artifactId>cloudant-client</artifactId>
-  <version>2.19.2</version>
+  <version>2.20.1</version>
 </dependency>
 
 <dependency>