Update url for stanford rare word(rw).zip

Summary:
The url for stanford rare word is no longer accurate as of date.
Closes https://github.com/facebookresearch/fastText/pull/80

Reviewed By: piotr-bojanowski

Differential Revision: D3900224

Pulled By: EdouardGrave

fbshipit-source-id: e22d48d0f5da2d540507f29e4b367a62c215256c

word-vector-example.sh

@@ -23,7 +23,7 @@ fi
 
 if [ ! -f "${DATADIR}/rw/rw.txt" ]
 then
-  wget -c http://www-nlp.stanford.edu/~lmthang/morphoNLM/rw.zip -P "${DATADIR}"
+  wget -c http://stanford.edu/~lmthang/morphoNLM/rw.zip -P "${DATADIR}"
   unzip "${DATADIR}/rw.zip" -d "${DATADIR}"
 fi