image/draw: add FloydSteinberg Drawer example
image/draw: add FloydSteinberg Drawer example

Updates #16360

Change-Id: I80b981aa291a8e16d2986d4a2dfd84d3819bf488
Reviewed-on: https://go-review.googlesource.com/29443
Run-TryBot: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Joe Tsai <7277d7402195d5c2006c89f45718cf82bb3e527f@gmail.com>

suncycheng/go,akutz/go,suncycheng/go,vsekhar/elastic-go,golang/go,Cofyc/go,momchil-velikov/go,nawawi/go,nawawi/go,Cofyc/go,golang/go,suncycheng/go,goodlang/good,ImJasonH/go,goodlang/good,derekmarcotte/go,goodlang/good,josharian/go,josharian/go,josharian/go,akutz/go,cloudflare/go,CAFxX/go,josharian/go,golang/go,linux-on-ibm-z/go,vsekhar/elastic-go,vsekhar/elastic-go,ImJasonH/go,cloudflare/go,josharian/go,Cofyc/go,derekmarcotte/go,ImJasonH/go,golang/go,linux-on-ibm-z/go,akutz/go,derekmarcotte/go,CAFxX/go,vsekhar/elastic-go,codestation/go,polyverse-security/go,cloudflare/go,akutz/go,vsekhar/elastic-go,josharian/go,nawawi/go,goodlang/good,Cofyc/go,goodlang/good,polyverse-security/go,codestation/go,codestation/go,derekmarcotte/go,polyverse-security/go,akutz/go,polyverse-security/go,Cofyc/go,nawawi/go,CAFxX/go,nawawi/go,codestation/go,momchil-velikov/go,linux-on-ibm-z/go,polyverse-security/go,Cofyc/go,codestation/go,Cofyc/go,CAFxX/go,momchil-velikov/go,goodlang/good,vsekhar/elastic-go,codestation/go,vsekhar/elastic-go,cloudflare/go,cloudflare/go,ImJasonH/go,ImJasonH/go,josharian/go,momchil-velikov/go,linux-on-ibm-z/go,linux-on-ibm-z/go,akutz/go,CAFxX/go,cloudflare/go,polyverse-security/go,golang/go,cloudflare/go,golang/go,momchil-velikov/go,golang/go,momchil-velikov/go,suncycheng/go,nawawi/go,polyverse-security/go,linux-on-ibm-z/go,Cofyc/go,linux-on-ibm-z/go,suncycheng/go,derekmarcotte/go,goodlang/good,CAFxX/go,nawawi/go,christopher-henderson/Go,ImJasonH/go,josharian/go,derekmarcotte/go,CAFxX/go,derekmarcotte/go,nawawi/go,akutz/go,suncycheng/go,codestation/go,momchil-velikov/go,polyverse-security/go,cloudflare/go,ImJasonH/go,suncycheng/go,momchil-velikov/go,suncycheng/go,vsekhar/elastic-go,derekmarcotte/go,golang/go,akutz/go,ImJasonH/go,codestation/go,CAFxX/go,goodlang/good,linux-on-ibm-z/go