swagger: clarify the meaning of Image field in ContainerInspect endpoint

"Container's image" term is rather ambiguous: it can be both a name and an ID.

Looking at the sources[1], it's actually an image ID, so bring some clarity.

[1]: https://github.com/moby/moby/blob/a6a47d1a4944799ffbe3657d4dae68e0829a0dc6/daemon/inspect.go#L170

Signed-off-by: Nikolay Edigaryev <edigaryev@gmail.com>
(cherry picked from commit c44fb423778e3d40cbc9e309d253067a5b8d4a96)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Upstream-commit: 700584104848be6401e0f85838cbaba39237080d
Component: engine

Author: edigaryev

components/engine/api/swagger.yaml

@@ -5014,7 +5014,7 @@ paths:
                 x-nullable: true
                 $ref: "#/definitions/ContainerState"
               Image:
-                description: "The container's image"
+                description: "The container's image ID"
                 type: "string"
               ResolvConfPath:
                 type: "string"