Fix #12528: Wrong instruction order for upgrade installations

doc/INSTALL

@@ -35,20 +35,23 @@ UPGRADING
 
  * Backup your existing installation and database -- really!
 
- * Extract the tarball into a clean directory; do not extract into an existing
+ * Extract the tarball into a clean directory; do NOT extract into an existing
    installation, as some files have been moved or deleted between releases
 
  * Copy your configuration from the old installation to the new directory,
    including config_inc.php, custom_strings_inc.php, and
    custom_constants_inc.php if they exist
 
- * Point your browser to http://path/to/mantisbt/admin/check.php to ensure that
-   your webserver is compatible with MantisBT and configured correctly
-
- * Point your browser to http://path/to/mantisbt/admin/install.php to upgrade
-   the database schema
+ * Point your browser to http://path/to/_NEW_mantisbt/admin/install.php to
+   upgrade the database schema
 
  * Click install/upgrade
 
- * Upgrading is complete
+ * Point your browser to http://path/to/_NEW_mantisbt/admin/check.php to ensure that
+   your webserver is compatible with MantisBT and configured correctly
+
+ * To restore your original MantisBT URL operation it is best at this point
+   to delete the old MantisBT directory and rename the directory you
+   extracted the tarball to to the original directory name.
 
+ * Upgrading is complete