docs: fix memory traces command

Type: fix

Change-Id: I8fc949da209a5067c702952fbd0e6ce77b921d02
Signed-off-by: Benoît Ganne <bganne@cisco.com>
diff --git a/docs/gettingstarted/troubleshooting/mem.rst b/docs/gettingstarted/troubleshooting/mem.rst
index 630b0af..1afe7b2 100644
--- a/docs/gettingstarted/troubleshooting/mem.rst
+++ b/docs/gettingstarted/troubleshooting/mem.rst
@@ -26,7 +26,7 @@
 
 .. code-block:: console
 
-    $ vppctl show memory-trace on main-heap
+    $ vppctl show memory main-heap verbose
     Thread 0 vpp_main
       base 0x7fffb6422000, size 1g, locked, unmap-on-destroy, name 'main heap'
 	page stats: page-size 4K, total 262144, mapped 30343, not-mapped 231801