internal/history: document Go 1.26.6 and Go 1.25.13

Change-Id: Icadc71e054e3197a15e86a1492f94b1d9027dc1e
Reviewed-on: https://go-review.googlesource.com/c/website/+/814880
Reviewed-by: Mark Freeman <mark@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
LUCI-TryBot-Result: golang-scoped@luci-project-accounts.iam.gserviceaccount.com <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

internal/history/release.go

diff --git a/internal/history/release.go b/internal/history/release.go
index 632a510..3aaaf39 100644
--- a/internal/history/release.go
+++ b/internal/history/release.go
@@ -14,6 +14,43 @@
 // The table is sorted by date, breaking ties with newer versions first.
 var Releases = []*Release{
 	{
+		Date: Date{2026, 8, 13}, Version: Version{1, 26, 6},
+		Security: &FixSummary{
+			Components: []template.HTML{"the <code>go</code> command"},
+			Packages: []string{
+				"crypto/tls",
+				"encoding/asn1",
+				"encoding/xml",
+				"html/template",
+				"net",
+				"net/http",
+				"net/url",
+			},
+		},
+		Bug: &FixSummary{
+			Components: []template.HTML{"the compiler", "the linker", "the runtime"},
+			Packages:   []string{"crypto/tls", "os"},
+		},
+	},
+	{
+		Date: Date{2026, 8, 13}, Version: Version{1, 25, 13},
+		Security: &FixSummary{
+			Components: []template.HTML{"the <code>go</code> command"},
+			Packages: []string{
+				"crypto/tls",
+				"encoding/asn1",
+				"encoding/xml",
+				"html/template",
+				"net/http",
+				"net/url",
+			},
+		},
+		Bug: &FixSummary{
+			Components: []template.HTML{"the compiler", "the runtime"},
+			Packages:   []string{"crypto/tls", "os"},
+		},
+	},
+	{
 		Date: Date{2026, 7, 7}, Version: Version{1, 26, 5},
 		Security: &FixSummary{
 			Packages: []string{