Fixed typo

[agilebuses20]

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Editing an existing topic or collection

I'm suggesting these edits to an existing topic or collection:

• Image (and my file is *.png, square, dimensions 288x288, size <= 75 kB)
• Content (and my changes are in index.md)

Fixed a typo in the dotfiles topic description; where it said "ususually", it has been replaced by "usually".

Curating a new topic or collection

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Something that does not neatly fit into the binary options above

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