internal/history: document Go 1.16

Change-Id: Ieb559df248ea4c7bdf23ef199e0520caf06a6de2
Reviewed-on: https://go-review.googlesource.com/c/website/+/292591
Trust: Alexander Rakoczy <alex@golang.org>
Run-TryBot: Alexander Rakoczy <alex@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Carlos Amedee <carlos@golang.org>
diff --git a/internal/history/release.go b/internal/history/release.go
index cfae1c0..7cd3aab 100644
--- a/internal/history/release.go
+++ b/internal/history/release.go
@@ -31,6 +31,10 @@
 // It contains entries for releases of Go 1.9 and newer.
 // Older releases are listed in doc/devel/release.html.
 var Releases = map[GoVer]Release{
+	{1, 16, 0}: {
+		Date: Date{2021, 2, 16},
+	},
+
 	{1, 15, 8}: {
 		Date: Date{2021, 2, 4},