docs: add go port to README

[nrednav]

Link to port: nrednav/cuid2

Apologies for yet another Go port of this library. I noticed the other implementations did not include a complete suite of tests and so I wanted to try my hand at recreating the full package, including collision tests.

I tried to incorporate as much as I could gather from the ongoing discussion in #33. Would greatly appreciate any feedback.

Todo / Missing

• Add histogram.go with tests for buildHistogram

[ericelliott]

I am not a go expert, but you could make the counter thread safe, right?

import "sync/atomic"

type Counter struct {
	value int64
}

func NewCounter(initialCount int64) *Counter {
	return &Counter{
		value: initialCount,
	}
}

func (c *Counter) Increment() int64 {
	return atomic.AddInt64(&c.value, 1)
}

[nrednav]

@ericelliott great suggestion, thanks! made the updates in: nrednav/cuid2#1 and nrednav/cuid2#2

[nrednav]

Package updated to include latest changes: nrednav/cuid2#5