Document Bug in EnMttag_GetCurrentCheckpoint and Cleanup

[inspectredc]

Not sure what the extent of the bug causes but surprised it doesn't cause crashes since from my understanding, the upper limit of the loop should be 3268542464 for sceneExitIndex 18.

[AngheloAlf]

Something to take in consideration that we are trying to get everybody who has contributed / wants to contribute to MM decomp to agree to licensing the repo before merging PRs from people who has not yet agreed to it. It is better explained here: https://github.com/louist103/mm-licensing/issues/1. Could you please read about it and post in that issue if you agree or not. Thanks!