doc: remove TODO from go1.4 release notes

LGTM=bradfitz
R=iant, rsc, bradfitz
CC=golang-codereviews
https://golang.org/cl/191750043

doc/go1.4.html

@@ -513,10 +513,7 @@ have been updated.
 <h3 id="swig">SWIG</h3>
 
 <p>
-Due to the runtime changes in this release, Go 1.4 will require SWIG 3.0.3.
-At time of writing that has not yet been released, but we expect it to be by
-Go 1.4's release date.
-TODO
+Due to runtime changes in this release, Go 1.4 requires SWIG 3.0.3.
 </p>
 
 <h3 id="misc">Miscellany</h3>