internal/history: document Go 1.15.3 and Go 1.14.10

Updates golang/go#41978
Updates golang/go#41977

Change-Id: I939fedfb5d5cb46622fbcbe139734b86ece8215c
Reviewed-on: https://go-review.googlesource.com/c/website/+/262377
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>
diff --git a/internal/history/release.go b/internal/history/release.go
index 3124046..27e2e09 100644
--- a/internal/history/release.go
+++ b/internal/history/release.go
@@ -31,6 +31,19 @@
 // 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, 15, 3}: {
+		Date: Date{2020, 10, 14},
+
+		Components: []template.HTML{"cgo", "the compiler", "runtime", "the <code>go</code> command"},
+		Packages:   []string{"bytes", "plugin", "testing"},
+	},
+	{1, 14, 10}: {
+		Date: Date{2020, 10, 14},
+
+		Components: []template.HTML{"the compiler", "runtime"},
+		Packages:   []string{"plugin", "testing"},
+	},
+
 	{1, 15, 2}: {
 		Date: Date{2020, 9, 9},