Add 'v1' plugin structure into man page

Change-Id: Ibb19d9bf0b164bdb840120e56e40c109b34b9a23
Reviewed-on: http://review.couchbase.org/28329
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Tested-by: Sergey Avseyev <sergey.avseyev@gmail.com>