docs: Fix effect -> affect typos

[teferi]

This PR fixes several typos in docs, where 'effect' was used incorrectly. Instead of a noun 'effect' this PR uses verb 'affect' where appropriate.

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[mathiasbynens]

Thanks! Could you please sign the CLA so we can merge this?

[jackfranklin]

@teferi ping on the CLA so we can ship this :)

[teferi]

@googlebot I signed it!

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[teferi]

@teferi ping on the CLA so we can ship this :)

done and done =)