Al,
Here is a link to the guide to writing documenation. All the docs are in Docbook XML. https://openacs.org/doc/current/docbook-primer.html
The originals are maintained in the acs-core-docs package for general documentation, and in each package under www/doc/ for package specific documentation. In general you should edit the XML source and new documentation will be generated. This is a little steep learning curve just to fix typos, I admit, so another alternative is to submit a bug report. If you feel ambitious, checkout the documentation from CVS and upload a patch file as well.
