The User Manual is now shipped with the source code, in DocBook format.
The Online version is here: HELP which is aligned to the code in the git master, so it may be in advance of the Viking version installed on your system.
Note that since this Wikized version is auto generated from the DocBook format it has some drawbacks:
It is not expected that the Wiki version will be edited in any meaningful way, as it will be periodically overwritten by an update from the DocBook version.
If you have Viking installed, simply run Viking and then request Help->Help menu.
You can also consult the PDF version available to download with each version released, since version 0.9.93 this is in the download files section.
The latest release is available directly HERE.
Of course, you can simply provide updates to the DocBook manual. http://viking.git.sourceforge.net/git/gitweb.cgi?p=viking/viking;a=tree;f=help
As DocBook is not really easy to hack, you can also simply provide updates in natural language, in the mailing-list or in the bug tracker. Some more skilled contributors will apply your comment in the DocBook files.
In order to make the help available without an internet connection, it requires the text to be distributed with the source for installation. However having a copy in the source and the Wiki can lead to divergence/maintenance effort to keep them aligned. Thus to have a single source for the User Manual, the DocBook method has been chosen to be the master (also the Wiki was not significantly changed in several months). An import of the previous Wiki User Manual was made and now has been 'removed'.