I know how to do this via SBT: Where does scaladoc look for the rootdoc.txt to create the root doc but cannot figure it out using Maven. Because of defects in SBT, I cannot use SBT for general builds.
Following http://davidb.github.io/scala-maven-plugin/example_doc.html I have the following in my pom.xml
<plugin>
<groupId>net.alchim31.maven</groupId>
<artifactId>scala-maven-plugin</artifactId>
<version>3.4.4</version>
<executions>
<execution>
<configuration>
<args>
<arg>-doc-root-content rootdoc.txt</arg>
</args>
<jvmArgs>
<jvmArg>-Xms1024m</jvmArg>
<jvmArg>-Xmx4096m</jvmArg>
</jvmArgs>
</configuration>
</execution>
</executions>
</plugin>
and
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-site-plugin</artifactId>
<version>3.0</version>
<configuration>
<reportPlugins>
<plugin>
<artifactId>maven-project-info-reports-plugin</artifactId>
<version>2.2</version>
</plugin>
<plugin>
<groupId>net.alchim31.maven</groupId>
<artifactId>scala-maven-plugin</artifactId>
<version>3.4.4</version>
<configuration>
<args>
<arg>-doc-root-content rootdoc.txt</arg>
</args>
<jvmArgs>
<jvmArg>-Xms64m</jvmArg>
<jvmArg>-Xmx1024m</jvmArg>
</jvmArgs>
</configuration>
</plugin>
...
</reportPlugins>
</configuration>
</plugin>
It would be really nice to include the root documentation for the API Docs, and not have to use SBT to generate the docs.