Add "stretch" variant for golang (1.8+)

library/golang

@@ -1,4 +1,4 @@
-# this file is generated via https://github.com/docker-library/golang/blob/f4a3691372cedcc546d7da35e30d961aec9ab04e/generate-stackbrew-library.sh
+# this file is generated via https://github.com/docker-library/golang/blob/e9c51096409712864189f9ed878a3f77c76ab101/generate-stackbrew-library.sh
 
 Maintainers: Tianon Gravi <[email protected]> (@tianon),
              Joseph Ferguson <[email protected]> (@yosifkit),
@@ -69,6 +69,10 @@ Tags: 1.8rc3-onbuild, 1.8-rc-onbuild, 1.8-onbuild, rc-onbuild
 GitCommit: f4a3691372cedcc546d7da35e30d961aec9ab04e
 Directory: 1.8-rc/onbuild
 
+Tags: 1.8rc3-stretch, 1.8-rc-stretch, 1.8-stretch, rc-stretch
+GitCommit: 8ee098f95a9b99552a157b5909e6916c9c181cc9
+Directory: 1.8-rc/stretch
+
 Tags: 1.8rc3-alpine, 1.8-rc-alpine, 1.8-alpine, rc-alpine
 GitCommit: f4a3691372cedcc546d7da35e30d961aec9ab04e
 Directory: 1.8-rc/alpine