http://api.mongodb.com/c/current/tutorial.html#creating-bson-documents

"See the libbson documentation for all of the types that can be appended to a bson_t."

This really should be link to the libbson docs, and the bson_t docs.

I think there should also be a more prominent link from the main reference page to libbson. Its such a fundamental part of mongoc it should be linked better.