Merge N experts notebook

[Stillerman]

Added a notebook that can merge N models on colab GPU and then upload it to the hub.

For issue #36

[mrcabbage972]

Hi @Stillerman ,
I have a couple of small requests:

• As we run a lot of our stuff in shell environments, it could be helpful if you coudconvert the notebook to a script
• Can you please remove the DS_store file for the PR?

Thanks!

[Stillerman]

Shell script produced this on the Redmond box with

python3 src/mdel/merge_experts.py --hf-repo Multi-Domain-Expert-Layers/merged-pubmed-freelaw -e Multi-Domain-Expert-Layers/expert-freelaw -e Multi-Domain-Expert-Layers/expert-pubmed_central

in ~2 mins

[mrcabbage972]

Thanks, merging!