Fix local docker image name for demos

[xfiderek]

Version or commit hash

23adec1

RMW Implementation

CycloneDDS

Steps to reproduce issue

1. Follow the tutorial for any of the demo dockers
2. Try building with space-ros:main
   https://github.com/space-ros/docker/blob/09ec4444add52d6b515e0549a4543c4dea792d5b/moveit2/README.md?plain=1#L17-L20

Expected behavior

The image name should be osrf/space-ros:main instead of space-ros:main

Actual behavior

The command fails because the image name is wrong.

Backtrace or Console output

No response