go spec: fix inaccuracy in type identity definition

Pointed out by Steven Blenkinsop (steven099@gmail.com)
via golang-nuts.

R=r, dsymonds
CC=golang-dev
https://golang.org/cl/5783087

doc/go_spec.html

 <!--{
 	"Title": "The Go Programming Language Specification",
-	"Subtitle": "Version of March 7, 2012",
+	"Subtitle": "Version of March 12, 2012",
 	"Path": "/ref/spec"
 }-->
 
@@ -1321,7 +1321,7 @@ Two types are either <i>identical</i> or <i>different</i>.
 
 <p>
 Two named types are identical if their type names originate in the same
-type <a href="#Declarations_and_scope">declaration</a>.
+<a href="#Type_declarations">TypeSpec</a>.
 A named and an unnamed type are always different. Two unnamed types are identical
 if the corresponding type literals are identical, that is, if they have the same
 literal structure and corresponding components have identical types. In detail: