Note integration sections in Gradle (#1898)

Author: Goooler

README.md

@@ -14,8 +14,8 @@ It's built on top of [Netty](https://github.com/netty/netty). It's compiled with
 Binaries are deployed on Maven Central.
 Add a dependency on the main AsyncHttpClient artifact:
 
+Maven:
 ```xml
-
 <dependencies>
     <dependency>
         <groupId>org.asynchttpclient</groupId>
@@ -25,6 +25,13 @@ Add a dependency on the main AsyncHttpClient artifact:
 </dependencies>
 ```
 
+Gradle:
+```groovy
+dependencies {
+    implementation 'org.asynchttpclient:async-http-client:3.0.0.Beta2'
+}
+```
+
 ## Version
 
 AHC doesn't use SEMVER, and won't.