Update leases-reclaim.json

doc/api/leases-reclaim.json

 {
     "name": "leases-reclaim",
     "brief": "The leases-reclaim command instructs the server to reclaim all expired leases immediately.",
-    "description": "See <xref linkend=\"leases-reclaim\"/>",
+    "description": "See <xref linkend=\"command-leases-reclaim\"/>",
     "support": [ "kea-dhcp4", "kea-dhcp6" ],
     "avail": "1.0.0",
     "cmd-syntax": "{