Rephrase documentation for fallbackSelection.

[palli]

The motivation here is a typo in the paragraph (attrForSelected), but also rephrase it a little bit as an attempt to make it clearer.

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[palli]

I signed it!

[TimvdLippe]

Thanks, is a lot clearer indeed!

[bicknellr]

Thanks!

[palli]

Thanks for mergin (one extra reply to get cla:yes)