[PATCH net-next] docs: net: document neigh gc_interval and gc_stale_time sysctls

[Gabriel Goller <g.goller@proxmox.com>]

Add missing documentation for two neighbor table garbage collector
sysctl parameters in ip-sysctl.rst:

 * neigh/default/gc_interval: controls how often the garbage collector
   runs for neighbor entries (default: 30 seconds)
 * neigh/default/gc_stale_time: controls how long an unused neighbor
   entry is kept before becoming eligible for garbage collection
   (default: 60 seconds)

Signed-off-by: Gabriel Goller <g.goller@proxmox.com>
---
 Documentation/networking/ip-sysctl.rst | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst
index 28c7e4f5ecf9..033e18303d79 100644
--- a/Documentation/networking/ip-sysctl.rst
+++ b/Documentation/networking/ip-sysctl.rst
@@ -202,6 +202,21 @@ neigh/default/gc_thresh3 - INTEGER
 
 	Default: 1024
 
+neigh/default/gc_interval - INTEGER
+	How often the garbage collector for neighbor entries should run. This
+	value applies to the entire table, not individual entries.
+
+	Default: 30 seconds
+
+neigh/default/gc_stale_time - INTEGER
+	Determines how long a neighbor entry can remain unused before it is
+	considered stale and eligible for garbage collection. Entries that have
+	not been used for longer than this time will be removed by the garbage
+	collector, unless they have active references, are marked as PERMANENT,
+	or carry the NTF_EXT_LEARNED or NTF_EXT_VALIDATED flag.
+
+	Default: 60 seconds
+
 neigh/default/unres_qlen_bytes - INTEGER
 	The maximum number of bytes which may be used by packets
 	queued for each	unresolved address by other network layers.
-- 
2.47.3