Add 1.3.0 upgrading docs

doc/80-Upgrading.md

@@ -3,6 +3,36 @@
 Upgrading Icinga Certificate Monitoring is straightforward.
 Usually the only manual steps involved are schema updates for the database.
 
+## Upgrading to version 1.3.0
+
+Icinga Certificate Monitoring version `1.3.0` requires a schema update for the database. We have dropped the use of **INI**
+files to store jobs and are using the database instead. So you need to migrate your job configs to the database.
+
+If you're already using Icinga Web 2 version `>= 2.12`, then you don't need to import the sql upgrade scripts manually.
+Icinga Web provides you the ability to perform such migrations in a simple way. You may be familiar with such an automation
+if you're an Icinga Director user. For those who are not using the latest version of Icinga Web, please follow the
+instructions below.
+
+Before migrating your jobs from **INI** to the database, you need to first apply the migration script. This will create
+the tables needed to store the jobs and schedules in the database.
+
+You may use the following command to apply the database schema upgrade file:
+<!-- {% if not icingaDocs %} -->
+
+**Note:** If you haven't installed this module from packages, then please adapt the schema path to the correct installation path.
+
+<!-- {% endif %} -->
+```sql
+# mysql -u root -p x509 < /usr/share/icingaweb2/modules/x509/schema/mysql-upgrades/1.3.0.sql
+```
+
+Afterward, you can safely migrate your jobs with the following command. Keep in mind that you need to specify an
+Icinga Web username that will be used as the author of these jobs in the database.
+
+```
+# icingacli x509 migrate jobs --author "icingaadmin"
+```
+
 ## Upgrading to version 1.2.0
 
 Icinga Certificate Monitoring version 1.2.0 requires a schema update for the database. We have changed all `timestamp`