Add repository to MR-Hub

[petravanhoudt]

https://ismrm.github.io/mrhub/

[ayudixit]

Hello dear, as i am going through it, I want to know exactly what are we looking for? If you'll give me overview then i can work on this.

[stadmill]

Hi @ayudixit, this issue will have to be addressed outside of this GitHub repo and is just reminder for the task force. No changes to the code are needed for this.