Add a util script for localization team

This PR adds a utility script for localization team to check changes
made to the English (upstream) source since last time the localized
version is updated (synchronized).

scripts/lsync.sh

@@ -0,0 +1,31 @@
+#!/bin/bash
+#
+# This script checks if the English version of a page has changed since a localized
+# page has been committed.
+
+if [ "$#" -ne 1 ] || ! [ -f "$1" ]; then
+  echo -e "\nThis script checks if the English version of a page has changed since a "
+  echo -e "localized page has been committed.\n"
+  echo -e "Usage:\n\t$0 <PATH>\n" >&2
+  echo -e "Example:\n\t$0 content/zh/docs/concepts/_index.md\n" >&2
+  exit 1
+fi
+
+LOCALIZED="$1"
+
+# Try get the English version
+EN_VERSION=`echo $LOCALIZED | sed "s/content\/..\//content\/en\//g"`
+if ! [ -f $EN_VERSION ]; then
+  echo "$EN_VERSION has been removed."
+  exit 2
+fi
+
+# Last commit for the localized file
+LASTCOMMIT=`git log -n 1 --pretty=format:%h -- $LOCALIZED`
+
+git diff $LASTCOMMIT...HEAD $EN_VERSION
+
+if [ "$?" -eq 0 ]; then
+  echo "$LOCALIZED is still in sync"
+  exit 3
+fi