There are in fact more books focused on Rails compared to Django, and this logically reflects the inferior documentation of Rails compared to Django, necessitating and creating a greater market for additional documentation. This market doesn't exist so much for Django not because of the lack of interest in learning Django, but because the documentation is so good. End of that story.
As for the greater perceived online presence of the Rails community, I think this reflects two things:
1) Greater confusion among Rails users, who as a general group seem less technically inclined "on the whole" (there are obviously a ton of brilliant Rails developers as well). In general, Rails users want things to be pre-configured for them, and therefore never really learn how things work under the hood, and are thus ill-equipped to make simple changes to their own apps.
2) Greater Apple-like fanboy-ism among Rails users, which takes on a religious fervor with people thinking they have met salvation, and it makes them feel special. They love to evangalize about it, and this personality trait in part the perceived greater popularity of Rails.
That said, both frameworks are obviously still very popular and effective at building web applications. Try both and go with whichever one you like better, and stop fretting about whether you've made the "right" decision.