Update CHANGELOG and README for release 20.0.0 (#650)

Author: jradcliff

CHANGELOG.md

@@ -1,3 +1,12 @@
+20.0.0 - 2022-07-19
+-------------------
+- Remove support for v9 of Google Ads API.
+- Add @Internal annotation for basePackage in Gradle (#647).
+- Add protobuf version to the API client header.
+- Rename GetArtifactMetadata to SearchForGoogleAdsFields and make the example
+  more flexible and useful.
+- Remove references to wrapper types.
+
 19.0.0 - 2022-06-15
 -------------------
 - Add support and examples for Google Ads API v11.0.

README.md

@@ -23,12 +23,12 @@ This project hosts the Java client library for the Google Ads API.
     <dependency>
       <groupId>com.google.api-ads</groupId>
       <artifactId>google-ads</artifactId>
-      <version>19.0.0</version>
+      <version>20.0.0</version>
     </dependency>
 
 ## Gradle dependency
 
-    implementation 'com.google.api-ads:google-ads:19.0.0'
+    implementation 'com.google.api-ads:google-ads:20.0.0'
 
 ## Documentation