Add additional notice before clone: `git-lfs` extension is required.

Why is this change being made?

Hey!

Yesterday I cloned this repository and after 3 hours of cloning process it failed with a message git-lfs: command not found.

I added a notice in README.md to inform people about this requirement before cloning proccess.

Does this MR meet the acceptance criteria?

Conformity

• Added description to this MR explaining the reasons for the proposed change, per say-why-not-just-what