Merb-related issues are managed at http://merb.lighthouseapp.com. You'll need to choose a product category from the several that are available on right-hand side of that page. Website-related problems are reported in the Merb website category. This category should not be used for bugs in merb itself, or the related gems. “Merb website” is for issues like:
It is probably 'not' worth filing bugs about incomplete documentation at this point, since there are a lot of APIs that need documentation. Rather than filing a ticket, if you can take the time to help flesh out the documentation anywhere you're able to, it would be appreciated by everyone. Ditto for requests for tutorials and how-to documents.