Fix build instructions for async client

OSS releases are rejected without source and javadoc artifacts.

Author: elreydetodo

edgegrid-signer-async-http-client/pom.xml

@@ -45,4 +45,17 @@
         </dependency>
     </dependencies>
 
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-javadoc-plugin</artifactId>
+            </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-source-plugin</artifactId>
+            </plugin>
+        </plugins>
+    </build>
+
 </project>