image: fix formatting of godoc link

Change-Id: I8fa8741e0db174f0c32af0a393ee1b037d5b7e51
Reviewed-on: https://go-review.googlesource.com/c/go/+/680455
Auto-Submit: Michael Knyszek <[email protected]>
Reviewed-by: Mark Freeman <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Roland Shoemaker <[email protected]>

Author: dolmen

src/image/image.go

@@ -34,7 +34,9 @@
 // regardless of whether the image is itself malformed or not. A call to
 // [DecodeConfig] which returns a header which does not match the image returned
 // by [Decode] may be considered a security issue, and should be reported per the
-// [Go Security Policy](https://go.dev/security/policy).
+// [Go Security Policy].
+//
+// [Go Security Policy]: https://go.dev/security/policy
 package image
 
 import (