Misleading organization and repository names will soon be changed

[ymd-stella]

I noticed that some people only watch openvslam_ros, so I'll mention it here as well.

stella-cv/stella_vslam#267

The organization name (OpenVSLAM-Community) and repository name (openvslam) will be changed due to the following issues:

Some people do not understand that it is a fork, even though it is mentioned in the README.
Some people have the misconception that the authors of the original version are still maintaining it.
The new organization/repository name will be stella-cv/stella_vslam.

The new organization/repository name of OpenVSLAM-Community/openvslam_ros will be stella-cv/stella_vslam_ros.

[ymd-stella]

Done.