New feature - Erase button to erase the digits

[arunkarthicknm]

The calculator is in need of erase button. :) If you find this as relevant, assign me, I can do it:)

[DhanushNehru]

Yes an eraze button, to remove digit by digit

You can do this, but make sure the position of new button is justifiable if created @arunkarthicknm

[DhanushNehru]

https://github.com/DhanushNehru/calculator/pull/12