Made documentation on migrations

Backend/Database/databaseMigration.php

@@ -1,7 +1,20 @@
 <?php
+//Path /Backend/Database/databaseMigration.php
 
-require "GameJam.php";
-require "GameData.php";
-require "Password.php";
-require "Group.php";
-require "KeyWord.php";
+/*
+ * databaseMigration is used to auto crate the various tables in the database.
+ * To call/run the databaseMigration visited the "Path".
+ * There is a reason to why we call GameJam first, the reason being
+ * that GameJam doesn't have any foreign key in the table, we can't
+ * create a table that depends on a foreign key, so we create all the tables
+ * without a foreign key in it, after that we are able to create the tables
+ * with foreign keys in it.
+ *
+ * See the Database Diagram for detailed understand.
+*/
+
+require "GameJam.php"; //GameJam has no foreign key
+require "GameData.php"; //GameData has no foreign key
+require "Password.php"; //Password has no foreign key
+require "Group.php"; //Group has foreign keys to the GameJam, GameData and Password tables hence we create it as one of the last tables in the database
+require "KeyWord.php"; //Group has foreign keys to the Group