README.md: bump Go compile-time dependency to 1.16 (#1884)
README.md: bump Go compile-time dependency to 1.16 (#1884)

Go 1.16 is required to build Please as of #1662 - update the
documentation to reflect this.
thought-machine/please,thought-machine/please,thought-machine/please,thought-machine/please,thought-machine/please,thought-machine/please