_content/doc/install/gccgo: update for GCC 10 and 11

Fixes golang/go#46420

Change-Id: Ic307699187864b398089d5973c0831a65560cf1e
Reviewed-on: https://go-review.googlesource.com/c/website/+/323130
Trust: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
diff --git a/_content/doc/install/gccgo.html b/_content/doc/install/gccgo.html
index 998c460..82d019b 100644
--- a/_content/doc/install/gccgo.html
+++ b/_content/doc/install/gccgo.html
@@ -75,6 +75,16 @@
 release.
 </p>
 
+<p>
+The GCC 10 releases include a complete implementation of the Go 1.14.6
+release.
+</p>
+
+<p>
+The GCC 11 releases include a complete implementation of the Go 1.16.3
+release.
+</p>
+
 <h2 id="Source_code">Source code</h2>
 
 <p>