Fix target_driver script producing suboptimal changelog file (#56)

Author: robsdedude

bin/target_driver.sh

@@ -13,5 +13,6 @@ git pull origin "$version"
 cd ..
 cp driver/tests/unit/common/codec/packstream/v1/test_packstream.py tests/v1/from_driver/test_packstream.py
 
-towncrier create -c "Target driver version ${version}<ISSUES_LIST>." "+.feature"
+towncrier create -c "Target driver version ${version}<ISSUES_LIST>.
+" "+.feature.md"
 echo "=== Please rename the changelog file to match the PR number. ==="