[release-branch.go1.14] doc/go1.14: document that freebsd/arm64 requires FreeBSD 12.0 or later

Updates #24715
Updates #37345

Change-Id: I787a9b2ab1c68e1d379aac0a31bdf6217f04f911
Reviewed-on: https://go-review.googlesource.com/c/go/+/220426
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
(cherry picked from commit 28c501b7b3405cf2afa7b9a440c9fc835d5276a0)
Reviewed-on: https://go-review.googlesource.com/c/go/+/220427
diff --git a/doc/go1.14.html b/doc/go1.14.html
index 90f52b0..9d5dff6 100644
--- a/doc/go1.14.html
+++ b/doc/go1.14.html
@@ -108,7 +108,7 @@
 <h3 id="freebsd">FreeBSD</h3>
 
 <p><!-- CL 199919 -->
-  Go now supports the 64-bit ARM architecture on FreeBSD (the
+  Go now supports the 64-bit ARM architecture on FreeBSD 12.0 or later (the
   <code>freebsd/arm64</code> port).
 </p>