title: Where can I find substantial, up-to-date Jenkins documentation?
body: <p>So we use Jenkins at work, and I'd like to really learn how it works, particularly so I could customize our builds with Jenkins' flavor of Groovy scripts, understand what all of the build scripts mean, etc.  But I just can't seem to find any solid, up-to-date documentation.  Here's where I've looked so far:</p>
  
  <ul>
  <li>I've read "Jenkins: The Definitive Guide" -- this is good as far as it goes, but it's outdated (2011) and doesn't seem to cover many of the current Jenkins features</li>
  <li>The documentation on jenkins.io -- this is pretty minimal and clearly a work in progress</li>
  <li>The wiki at wiki.jenkins-ci.org -- this has more information than jenkins.io, but seems to be mostly focused articles on specific topics, without a comprehensive discussion of how it all works</li>
  <li>Stack Overflow -- there are a few questions on Jenkins documentation for specific use cases (e.g. writing a plugin), but as far as I can tell, none of those answers point to general, comprehensive documentation</li>
  </ul>
  
  <p>I feel like I must be just missing something, since so many people use Jenkins -- they must be figuring out how to use it somehow.</p>