go.talks/2012/splash.article: fix typo

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/10365054
diff --git a/2012/splash.article b/2012/splash.article
index 377bc15..d0ebe00 100644
--- a/2012/splash.article
+++ b/2012/splash.article
@@ -812,7 +812,7 @@
 software, it is our opinion that the model has been overused and that it
 is worth taking a step back.
 
-Instead, Go has _interfaces_, an idea that as been discussed at length elsewhere (see
+Instead, Go has _interfaces_, an idea that has been discussed at length elsewhere (see
 [[http://research.swtch.com/interfaces][research.swtch.com/interfaces]]
 for example), but here is a brief summary.