It's not on the Cocoapods site yet as it in early developer preview. But you can pull it in directly from the repo:
pod 'CouchbaseLite', :git => 'https://github.com/couchbase/couchbase-lite-ios.git', :tag => '2.0DB1', :submodules => true
Note that 2.0 is currently in early developer preview (iOS only) and not all features are in this build (developer build 1). The details are in the docs linked above. That being said, it's worth giving it a try to see if it works for you. We will also add this pod line in the developer preview docs.