While the .txt file itself is not the mod, it usually contains:
Are you having trouble getting a to show up in your game? Download File _K & SIDER VERSION FACE NEW V04.txt
Many "V04" packs use the player's original game IDs, meaning you don't need to manually change ID numbers in external editors for the faces to show up. While the
A list of the "facemakers" (artists) who created the digital models. Common Troubleshooting Download File _K & SIDER VERSION FACE NEW V04.txt
It includes updated facial models and textures for a specific set of players, often including young or newly debuted stars.