Please provide a basic Maven example

[lukehutch]

Please provide basic Maven (and/or Gradle) code for including some or all artifacts in this project, in the README.md. This is what I came up with (I'm not submitting it as a PR since it works, but I want to verify that this is the right way to do things):

<project xmlns="http://maven.apache.org/POM/4.0.0"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>GROUP_ID</groupId>
	<artifactId>ARTIFACT_ID</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<repositories>
		<repository>
			<id>ros</id>
			<name>ros</name>
			<url>https://github.com/rosjava/rosjava_mvn_repo/raw/master</url>
		</repository>
		<repository>
			<id>repository.spring.libs-release</id>
			<name>Spring Libs Repository</name>
			<url>https://repo.spring.io/libs-release</url>
		</repository>
	</repositories>
	<dependencies>
		<dependency>
			<groupId>org.ros.rosjava_core</groupId>
			<artifactId>rosjava</artifactId>
			<version>0.3.6</version>
		</dependency>
		<dependency>
			<groupId>org.ros.rosjava_messages</groupId>
			<artifactId>std_msgs</artifactId>
			<version>0.5.11</version>
		</dependency>
		<dependency>
			<groupId>org.ros.rosjava_messages</groupId>
			<artifactId>sensor_msgs</artifactId>
			<version>1.12.7</version>
		</dependency>
		<dependency>
			<groupId>org.ros.rosjava_messages</groupId>
			<artifactId>sensor_msgs</artifactId>
			<version>1.12.7</version>
		</dependency>
		<dependency>
			<groupId>org.ros.rosjava_bootstrap</groupId>
			<artifactId>message_generation</artifactId>
			<version>0.3.3</version>
		</dependency>
	</dependencies>
	<build>
		<sourceDirectory>src</sourceDirectory>
		<plugins>
			<plugin>
				<artifactId>maven-compiler-plugin</artifactId>
				<version>3.8.0</version>
				<configuration>
					<release>11</release>
				</configuration>
			</plugin>
		</plugins>
	</build>
</project>

Probably you should have an example containing all current artifacts and versions, so users can easy select just the packages they need by deleting the ones they don't need.