doc/code.html: fix reference to "gomake build"

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/3288042

doc/code.html

@@ -192,7 +192,7 @@ GOFILES=\
 include $(GOROOT)/src/Make.cmd
 </pre>
 
-<p>Running <code>gomake build</code> will compile <code>helloworld.go</code>
+<p>Running <code>gomake</code> will compile <code>helloworld.go</code>
 and produce an executable named <code>helloworld</code> in the current
 directory.
 </p>