According to 'Doxygen and comment formatting conventions' : http://drupal.org/node/1354
"Everything between @link and @endlink needs to be on one line. The line is allowed to exceed 80 characters, but if it does, it should be by itself on the line (break surrounding text before/after the link line)."

I have included a link on its own line as shown in the Doxygen example given.
Unlike the example mine exceeds 80 characters which should be allowed but it triggers the error: "Function documentation should be less than 80 characters per line"

* @link http://wiki.civicrm.org/confluence/display/CRMDOC40/CiviCRM+hook+specification#CiviCRMhookspecification-hookcivicrmpostProcess CiviCRM Hook Post Process Documentation @endlink

PS - Thanks for the tough love ;)
It has greatly improved my code's documentation and readability.