* add feature request #3084

* Update contracts/token/ERC20/ERC20.sol

Co-authored-by: Francisco Giordano <frangio.1@gmail.com>

* Add changelog note

* add documentation

* test unlimitted allowance and add ERC777 unlimitted allowance

* reference PR in changelog

* documentation IERC20 -> ERC20

* use asciidoc note syntax

* use asciidoc note syntax

* typo

* typos

Co-authored-by: Hadrien Croubois <hadrien.croubois@gmail.com>
Co-authored-by: Francisco Giordano <frangio.1@gmail.com>