fixed a typo

R=r
DELTA=1  (0 added, 0 deleted, 1 changed)
OCL=25449
CL=25449

doc/go_spec.html

@@ -560,7 +560,7 @@ because the size of the pointer itself is always known.
 The <i>interface</i> of a type is the set of methods bound to it
 (§Method declarations); for pointer types, it is the interface
 of the pointer base type (§Pointer types). All types have an interface;
-if they have no methods, it is the <i>empty'' interface</i>.
+if they have no methods, it is the <i>empty interface</i>.
 </p>
 <p>
 The <i>static type</i> (or just <i>type</i>) of a variable is the