Barbican has an in-tree API reference and an api-guide on developer.o.o.
Both show up on the index page as "API Guide". Rename the in-tree
document to "API Documentation" to differentiate it from the others in
case teams have both in-tree and out-of-tree docs.
Change-Id: I80b51cea1898a7cf5c3f254d42b7a86d0c67e2b0
ffe3e6970e