README.md: bump supported go version to 1.12+
Change-Id: I8cee9dec3ec13dceb19945135d078444f02a10e4
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/3862
Reviewed-by: Marcel van Lohuizen <mpvl@golang.org>
diff --git a/README.md b/README.md
index e67c6c0..f23c48f 100644
--- a/README.md
+++ b/README.md
@@ -16,7 +16,7 @@
[](https://godoc.org/cuelang.org/go)
[](https://github.com/cuelang/cue/actions)
[](https://goreportcard.com/report/github.com/cuelang/cue)
-[](https://golang.org/dl/)
+[](https://golang.org/dl/)
[]()