Add results for R2MED benchmark

[ll0ruc]

Checklist

• The results submitted is obtained using the reference implementation
• My model is available, either as a publicly accessible API or publicly on e.g., Huggingface
• I solemnly swear that for all results submitted I have not on the evaluation dataset including training splits. If I have I have disclosed it clearly.

[KennethEnevoldsen]

Sorry @ll0ruc I accidentally merged this, so I had to revert the change. I sadly can't re-open the PR, but please do re-open.

I btw. can't find R2MEDRetrieval in the mteb. Seems like you might need to create a PR for it