docs: add descriptions of local files

docs/local-files.md

@@ -0,0 +1,9 @@
+# Local Files
+
+Kube-OVN will store files to the host filesystem. Administrators should take care of these locations to avoid malicious application access to them or accidentally delete them.
+
+* `/etc/origin/ovn` and `/etc/origin/openvswitch` store the OVN and OVS db files. These files store the logical network topology.
+* `/var/run/ovn` and `/var/run/openvswitch` store the OVN and OVS socket files. These files provide endpoints to OVN/OVS control plane.
+* `/var/log/ovn` and `/var/log/openvswitch` store the log files of OVN and OVS.
+* `/etc/cni/net.d` stores the Kube-OVN CNI conf.
+* `/etc/cni/bin` stores the Kube-OVN CNI binary.