removed 'format()' function from the README as this function doesn't exists

[sheepbild]

Following to this issue : https://github.com/MedicOneSystems/livewire-datatables/issues/490#issue-1326159919

This is my first pull request on GitHub, a simple correction in the README but this is a beginning ! :) IDK what are the "analysis" branchs, so i took the last, if someone can explain to me what it means