doc/go_faq.html: fix non-grammatical sentence

With my apologies.

R=golang-dev, alex.brainman
CC=golang-dev
https://golang.org/cl/12984045

doc/go_faq.html

@@ -480,7 +480,7 @@ to start talking about what that might be.
 </p>
 
 <p>
-Even if your proposal is compatible with the Go 1 spec, it may be
+Even if your proposal is compatible with the Go 1 spec, it might
 not be in the spirit of Go's design goals.
 The article <i><a href="http://talks.golang.org/2012/splash.article">Go
 at Google: Language Design in the Service of Software Engineering</a></i>