Split README into a bunch of files in docs/

docs/maintenance-upgrading-services.md

@@ -0,0 +1,15 @@
+# Upgrading the Matrix services
+
+This playbook not only installs the various Matrix services for you, but can also upgrade them as new versions are made available.
+
+To upgrade the services:
+
+- update your playbook directory (`git pull`), so you'd obtain everything new we've done
+
+- take a look at [the changelog](../CHANGELOG.md) to see if there have been any backward-incomptabile changes that you need to take care of
+
+- re-run the [playbook setup](installing.md): `ansible-playbook -i inventory/hosts setup.yml --tags=setup-all`
+
+- restart the services: `ansible-playbook -i inventory/hosts setup.yml --tags=start`
+
+**Note**: major version upgrades are not done to the internal PostgreSQL database. To upgrade that one, refer to the [upgrading PostgreSQL document](maintenance-upgrading-postgres.md).