tools: add 'nfdc cs config' command

refs #4050

Change-Id: Ifc49b78a286b1947452d3d7917b5937b95d1bfe5
diff --git a/docs/manpages/nfdc-cs.rst b/docs/manpages/nfdc-cs.rst
index 4ff387c..99b46d8 100644
--- a/docs/manpages/nfdc-cs.rst
+++ b/docs/manpages/nfdc-cs.rst
@@ -1,14 +1,30 @@
 nfdc-cs
-===========
+=======
 
 SYNOPSIS
 --------
 | nfdc cs [info]
+| nfdc cs config [capacity <CAPACITY>] [admit on|off] [serve on|off]
 
 DESCRIPTION
 -----------
 The **nfdc cs info** command shows CS statistics information.
 
+The **nfdc cs config** command updates CS configuration.
+
+OPTIONS
+-------
+<CAPACITY>
+    Maximum number of Data packets the CS can store.
+    Lowering the capacity causes the CS to evict excess Data packets.
+
+admit on|off
+    Whether the CS can admit new Data.
+
+serve on|off
+    Whether the CS can satisfy incoming Interests using cached Data.
+    Turning this off causes all CS lookups to miss.
+
 SEE ALSO
 --------
 nfd(1), nfdc(1)