docs: add ref for sysadmin host admin section

Signed-off-by: Aaron Lauterer <a.lauterer@proxmox.com>

docs/sysadmin.rst

@@ -1,3 +1,5 @@
+.. _sysadmin_host_administration:
+
 Host System Administration
 ==========================
 

www/OnlineHelpInfo.js

@@ -123,6 +123,10 @@ const proxmoxOnlineHelpInfo = {
     "link": "/docs/storage.html#storage-datastore-create",
     "title": "Creating a Datastore"
   },
+  "sysadmin-host-administration": {
+    "link": "/docs/sysadmin.html#sysadmin-host-administration",
+    "title": "Host System Administration"
+  },
   "user-mgmt": {
     "link": "/docs/user-management.html#user-mgmt",
     "title": "User Management"