Update instructions for building libcouchbase to be more verbose

http://www.couchbase.com/docs/couchbase-sdk-c-1.0/linux_and_mac.html

This guy was a little bit confused about how to build because the first step wasn't to run config/autorun.sh. We should add that to the documentation.

Also, I think we should add the stuff that is in the comments to the docs. We should give the locations of where the downloads are. There is also no mention of needing memcached installed. This is a requirement since libcouchbase depends on memcached/protocol_binary.h.