check_staged_release: reject index.html.tmp

For some time I noticed that wget places index.html.tmp files in the
download directory. These are useless and show be rejected.
diff --git a/check_staged_release.sh b/check_staged_release.sh
index 02a9c41..ca2c4d8 100755
--- a/check_staged_release.sh
+++ b/check_staged_release.sh
@@ -16,7 +16,7 @@
  echo "                           DOWNLOAD STAGED REPOSITORY                           "
  echo "################################################################################"
 
- wget -e "robots=off" --wait 1 -nv -r -np "--reject=html" "--follow-tags=" \
+ wget -e "robots=off" --wait 1 -nv -r -np "--reject=html,index.html.tmp" "--follow-tags=" \
   -P "${DOWNLOAD}/${STAGING}" -nH "--cut-dirs=3" \
   "https://repository.apache.org/content/repositories/orgapachesling-${STAGING}/org/apache/sling/"