Fix json examples in the api reference.

Signed-off-by: David Calavera <david.calavera@gmail.com>
Upstream-commit: 7296c845b739ae4133e3d02d56cb7e8df29eb020
Component: engine

components/engine/docs/reference/api/docker_remote_api_v1.18.md

@@ -193,7 +193,7 @@ Create a container
         Content-Type: application/json
 
         {
-             "Id":"e90e34656806"
+             "Id":"e90e34656806",
              "Warnings":[]
         }
 
@@ -1872,7 +1872,7 @@ Sets up an exec instance in a running container `id`
         Content-Type: application/json
 
         {
-             "Id": "f90e34656806"
+             "Id": "f90e34656806",
              "Warnings":[]
         }