Add template for upgrading between versions of Apache AGE

.gitignore

@@ -1,10 +1,11 @@
 *.o
 *.so
 build.sh
-age--*.*.*.sql
 .idea
 .deps
 .DS_Store
 *.tokens
 *.interp
 *.dylib
+age--*.*.*.sql
+!age--*--*sql

age--1.5.0--y.y.y.sql

@@ -0,0 +1,30 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+-- This is a template for upgrading from the previous version of Apache AGE
+-- It will only work within versions of PostgreSQL, not across.
+-- Please adjust the below ALTER EXTENSION to reflect the correct version
+-- it is upgrading to.
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "ALTER EXTENSION age UPDATE TO '1.4.0'" to load this file. \quit
+
+-- Please add all additions, deletions, and modifications to the end of this
+-- file. We need to keep the order of these changes.
+