added back comments to satisfy docs

Signed-off-by: Richard Jones <richard@dagger.io>

stdlib/europa/dagger/plan.cue

@@ -4,4 +4,8 @@ import (
 	"alpha.dagger.io/europa/dagger/engine/spec/engine"
 )
 
+// A deployment plan executed by `dagger up`
 #Plan: engine.#Plan
+
+// A special kind of program which `dagger` can execute.
+#DAG: engine.#DAG

stdlib/europa/dagger/types.cue

@@ -26,6 +26,8 @@ import (
 //  - An HTTPS endpoint
 #Service: engine.#Service
 
+// A stream of bytes
 #Stream: engine.#Stream
 
+// A network service address
 #Address: engine.#Address