This plugin has been removed from the current Maven distribution, it is not maintained by the Maven team anymore. Please check the Plugins History page to find out the last Maven version that included this plugin.
Ashkelon is "an online reference tool for java api documentation. Ashkelon is javadoc taken the next step of being able to reference multiple API's (>100,000 methods) in a single, fully cross-referenced and searchable database repository."
Maven's Ashkelon Plugin provides a set of goals to integrate your project's javadocs to Ashkelon.