This is problematic and as far as I know impossible on github or any other git host. While git can be used for versioning, things like git diff will return differences between the two versions in text form. Illegible.
I feel that this is not without reason. There are unlimited file formats in the world, and many of them are property. Thus, instead of supporting each format, such as VLC, git uses text files for everything.
In addition, even if git somehow supports docx, it will not be able to display formatting changes inside the terminal, not to mention cmd. If this is just text, it is best to save it as a text file. Or manually check the previous version to compare the changes.
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