Add Fine-tuning Example

[JinyuanSun]

Addresses the discussion in issue #11 by introducing a new example script for fine-tuning the evo-1-8k-base model on the human-genome-cds.

[xiyang-aads-lilly]

@JinyuanSun Hi Sun,

I wonder if you tried to train full parameters with large seq len? The example here only train the last layer.