Tag new version dev/release/release.sh (#381)

fixes #380
diff --git a/dev/release/release.sh b/dev/release/release.sh
index b597962..a09ca4a 100755
--- a/dev/release/release.sh
+++ b/dev/release/release.sh
@@ -28,6 +28,12 @@
 version=$1
 rc=$2
 
+rc_tag="v${version}-rc${rc}"
+release_tag="v${version}"
+echo "Tagging for release: ${release_tag}"
+git tag -a -m "${version}" "${release_tag}" "${rc_tag}^{}"
+git push origin "${release_tag}"
+
 rc_id="apache-arrow-julia-${version}-rc${rc}"
 release_id="arrow-julia-${version}"
 echo "Move from dev/ to release/"