README: mention current Go 2 process

Updates golang/go#29860

Change-Id: I442ed5d8d5bfe26abdfc93059b1c57b09fb00c8a
Reviewed-on: https://go-review.googlesource.com/c/158843
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
diff --git a/README.md b/README.md
index acfaa75..ded3fd8 100644
--- a/README.md
+++ b/README.md
@@ -80,10 +80,16 @@
 
 ### Language changes
 
-Go is a mature language and, as such, significant language changes are unlikely
-to be accepted.
-A "language change" in this context means a change to the
-[Go language specification](https://golang.org/ref/spec).
+In 2018 we started a Go 2 process during which we may change the
+language, as described on [the Go
+blog](https://blog.golang.org/go2-here-we-come).
+Language changes should follow the proposal process described here.
+As explained in the blog entry, language change proposals should
+
+- address an important issue for many people,
+- have minimal impact on everybody else, and
+- come with a clear and well-understood solution.
+
 (See the [release notes](https://golang.org/doc/devel/release.html) for
 examples of recent language changes.)