Add Wan 2.1 convergence comparison documentation (#74)

- Introduced a new document detailing the comparison between Diffusers (Automodel path) and Megatron-Core (Megatron-Bridge path) for Wan 2.1.
- Included experiment overview, dataset specifications, training setup, and results with visual training curves.
- Added two binary images illustrating loss vs. steps for both text-to-image and text-to-video stages.

This documentation aims to provide insights into the model's performance and training dynamics during the partial convergence test.

Author: abhinavg4