Changes to the documentation can be requested to the issue tracker, or added to a page as a comment. To add comments, create an account on the Struts 2 Documentation Confluence space at cwiki.apache.org. A volunteer with page editing privileges can then make the change by referring to the comment. (Confluence sends to the developers mailing list a daily summary of changes, including new comments.)
To request page editing privileges, first file a Contributor's Licence License Agreement with the ASF. After CLA is submitted (fax is still best), you can request a karma upgrade on the dev list. After the CLA is submitted, it make take several days for it to be processed by the ASF Secretary (who is a part time volunteer, like everyone else around here). The roster of CLAs is available to ASF members, as well as at the bottom of this page, so we will know when it is processed.
Sadly, not everyone can file a CLA. Many organizations still use aggressive IP agreement that assign rights to our every stray thought to the company, 24/7. In fact, some organizations grant a special dispensation for the ASF so that their employees can file CLAs.