Add styles for level 5 and 6 headers.
Add styles for level 5 and 6 headers.

cfengine/documentation-generator,stweil/documentation-generator,stweil/documentation-generator,michaelclelland/documentation-generator,stweil/documentation-generator,stweil/documentation-generator,michaelclelland/documentation-generator,stweil/documentation-generator,nickanderson/documentation-generator,nickanderson/documentation-generator,michaelclelland/documentation-generator,nickanderson/documentation-generator,cfengine/documentation-generator,nickanderson/documentation-generator,michaelclelland/documentation-generator,michaelclelland/documentation-generator,cfengine/documentation-generator,nickanderson/documentation-generator,cfengine/documentation-generator,cfengine/documentation-generator