Added Indentation section to document the exact exapected behavior of…

[mipo256]

As discussed in this issue, there turned out to be a lot of undocumented behavior in terms of indentation style in use. This PR aims to address the problem mentioned in the aforementioned issue by documenting the behavior of indentation options.

CC: @xuhdev

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📚 Documentation preview 📚: https://editorconfig-specification--65.org.readthedocs.build/