Update readme.md (#1075)
Update readme.md (#1075)

Clarify that context is initialized anew for each test.
sindresorhus/ava,andywer/ava-ts,avajs/ava,Collinslenjo/ava,Collinslenjo/ava,andywer/ava-ts,avajs/ava,BarryThePenguin/ava