update docs

docs/20_Checks/_index.md

@@ -9,7 +9,8 @@ There is one include script used by all checks:
 
 * [check_apache_requests](check_apache_requests.md)
 * check_backup_one
-* check_ceph_diskfree
+* [check_ceph_diskfree](check_ceph_diskfree.md)
+* [check_ceph_io](check_ceph_io.md)
 * check_ceph_osd
 * check_ceph_status
 * check_clientbackup
@@ -33,7 +34,7 @@ There is one include script used by all checks:
 * check_sensuplugins
 * check_smartstatus
 * [check_snmp_data](check_snmp_data.md)
-* check_snmp_synology
+* [check_snmp_synology](check_snmp_synology.md)
 * check_ssl
 * check_systemdservices
 * check_timesync